Related
I have the following table
"phone_number_info"
id uuid
country character
phone_number text
page_views bigint
I have the following query which is supposed to insert a row into the table, and if it already exists, increase the page_views count
INSERT INTO phone_number_info (country, phone_number) VALUES('us', '1234567890')
ON CONFLICT (country, phone_number)
DO UPDATE SET phone_number_info.page_views = (phone_number_info.page_views + 1);
When executing the query above, I get the following message
Error in query: ERROR: column "phone_number_info" of relation "phone_number_info" does not exist
LINE 3: DO UPDATE SET phone_number_info.page_views = (phone_number_i...
What is wrong with the query?
The column identifiers in the SET clauses cannot be not qualified with the table name - they always refer to the updated table. So use
INSERT INTO phone_number_info (country, phone_number) VALUES('us', '1234567890')
ON CONFLICT (country, phone_number)
DO UPDATE SET page_views = (phone_number_info.page_views + 1);
^^^^^^^^^^^^^^^^
I'm getting the following error when doing the following type of insert:
Query:
INSERT INTO accounts (type, person_id) VALUES ('PersonAccount', 1) ON
CONFLICT (type, person_id) WHERE type = 'PersonAccount' DO UPDATE SET
updated_at = EXCLUDED.updated_at RETURNING *
Error:
SQL execution failed (Reason: ERROR: there is no unique or exclusion
constraint matching the ON CONFLICT specification)
I also have an unique INDEX:
CREATE UNIQUE INDEX uniq_person_accounts ON accounts USING btree (type,
person_id) WHERE ((type)::text = 'PersonAccount'::text);
The thing is that sometimes it works, but not every time. I randomly get
that exception, which is really strange. It seems that it can't access that
INDEX or it doesn't know it exists.
Any suggestion?
I'm using PostgreSQL 9.5.5.
Example while executing the code that tries to find or create an account:
INSERT INTO accounts (type, person_id, created_at, updated_at) VALUES ('PersonAccount', 69559, '2017-02-03 12:09:27.259', '2017-02-03 12:09:27.259') ON CONFLICT (type, person_id) WHERE type = 'PersonAccount' DO UPDATE SET updated_at = EXCLUDED.updated_at RETURNING *
SQL execution failed (Reason: ERROR: there is no unique or exclusion constraint matching the ON CONFLICT specification)
In this case, I'm sure that the account does not exist. Furthermore, it never outputs the error when the person has already an account. The problem is that, in some cases, it also works if there is no account yet. The query is exactly the same.
Per the docs,
All table_name unique indexes that, without regard to order, contain exactly the
conflict_target-specified columns/expressions are inferred (chosen) as arbiter
indexes. If an index_predicate is specified, it must, as a further requirement
for inference, satisfy arbiter indexes.
The docs go on to say,
[index_predicate are u]sed to allow inference of partial unique indexes
In an understated way, the docs are saying that when using a partial index and
upserting with ON CONFLICT, the index_predicate must be specified. It is not
inferred for you. I learned this
here, and the following example demonstrates this.
CREATE TABLE test.accounts (
id int PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
type text,
person_id int);
CREATE UNIQUE INDEX accounts_note_idx on accounts (type, person_id) WHERE ((type)::text = 'PersonAccount'::text);
INSERT INTO test.accounts (type, person_id) VALUES ('PersonAccount', 10);
so that we have:
unutbu=# select * from test.accounts;
+----+---------------+-----------+
| id | type | person_id |
+----+---------------+-----------+
| 1 | PersonAccount | 10 |
+----+---------------+-----------+
(1 row)
Without index_predicate we get an error:
INSERT INTO test.accounts (type, person_id) VALUES ('PersonAccount', 10) ON CONFLICT (type, person_id) DO NOTHING;
-- ERROR: there is no unique or exclusion constraint matching the ON CONFLICT specification
But if instead you include the index_predicate, WHERE ((type)::text = 'PersonAccount'::text):
INSERT INTO test.accounts (type, person_id) VALUES ('PersonAccount', 10)
ON CONFLICT (type, person_id)
WHERE ((type)::text = 'PersonAccount'::text) DO NOTHING;
then there is no error and DO NOTHING is honored.
A simple solution of this error
First of all let's see the cause of error with a simple example. Here is the table mapping products to categories.
create table if not exists product_categories (
product_id uuid references products(product_id) not null,
category_id uuid references categories(category_id) not null,
whitelist boolean default false
);
If we use this query:
INSERT INTO product_categories (product_id, category_id, whitelist)
VALUES ('123...', '456...', TRUE)
ON CONFLICT (product_id, category_id)
DO UPDATE SET whitelist=EXCLUDED.whitelist;
This will give you error No unique or exclusion constraint matching the ON CONFLICT because there is no unique constraint on product_id and category_id. There could be multiple rows having the same combination of product and category id (so there can never be a conflict on them).
Solution:
Use unique constraint on both product_id and category_id like this:
create table if not exists product_categories (
product_id uuid references products(product_id) not null,
category_id uuid references categories(category_id) not null,
whitelist boolean default false,
primary key(product_id, category_id) -- This will solve the problem
-- unique(product_id, category_id) -- OR this if you already have a primary key
);
Now you can use ON CONFLICT (product_id, category_id) for both columns without any error.
In short: Whatever column(s) you use with on conflict, they should have unique constraint.
The easy way to fix it is by setting the conflicting column as UNIQUE
I did not have a chance to play with UPSERT, but I think you have a case from
docs:
Note that this means a non-partial unique index (a unique index
without a predicate) will be inferred (and thus used by ON CONFLICT)
if such an index satisfying every other criteria is available. If an
attempt at inference is unsuccessful, an error is raised.
I solved the same issue by creating one UNIQUE INDEX for ALL columns you want to include in the ON CONFLICT clause, not one UNIQUE INDEX for each of the columns.
CREATE TABLE table_name (
element_id UUID NOT NULL DEFAULT gen_random_uuid(),
timestamp TIMESTAMP NOT NULL DEFAULT now():::TIMESTAMP,
col1 UUID NOT NULL,
col2 STRING NOT NULL ,
col3 STRING NOT NULL ,
CONSTRAINT "primary" PRIMARY KEY (element_id ASC),
UNIQUE (col1 asc, col2 asc, col3 asc)
);
Which will allow to query like
INSERT INTO table_name (timestamp, col1, col2, col3) VALUES ('timestamp', 'uuid', 'string', 'string')
ON CONFLICT (col1, col2, col3)
DO UPDATE timestamp = EXCLUDED.timestamp, col1 = EXCLUDED.col1, col2 = excluded.col2, col3 = col3.excluded;
I have two columns in table col1, col2, they both are unique indexed (col1 is unique and so is col2).
I need at insert into this table, use ON CONFLICT syntax and update other columns, but I can't use both column in conflict_targetclause.
It works:
INSERT INTO table
...
ON CONFLICT ( col1 )
DO UPDATE
SET
-- update needed columns here
But how to do this for several columns, something like this:
...
ON CONFLICT ( col1, col2 )
DO UPDATE
SET
....
ON CONFLICT requires a unique index* to do the conflict detection. So you just need to create a unique index on both columns:
t=# create table t (id integer, a text, b text);
CREATE TABLE
t=# create unique index idx_t_id_a on t (id, a);
CREATE INDEX
t=# insert into t values (1, 'a', 'foo');
INSERT 0 1
t=# insert into t values (1, 'a', 'bar') on conflict (id, a) do update set b = 'bar';
INSERT 0 1
t=# select * from t;
id | a | b
----+---+-----
1 | a | bar
* In addition to unique indexes, you can also use exclusion constraints. These are a bit more general than unique constraints. Suppose your table had columns for id and valid_time (and valid_time is a tsrange), and you wanted to allow duplicate ids, but not for overlapping time periods. A unique constraint won't help you, but with an exclusion constraint you can say "exclude new records if their id equals an old id and also their valid_time overlaps its valid_time."
A sample table and data
CREATE TABLE dupes(col1 int primary key, col2 int, col3 text,
CONSTRAINT col2_unique UNIQUE (col2)
);
INSERT INTO dupes values(1,1,'a'),(2,2,'b');
Reproducing the problem
INSERT INTO dupes values(3,2,'c')
ON CONFLICT (col1) DO UPDATE SET col3 = 'c', col2 = 2
Let's call this Q1. The result is
ERROR: duplicate key value violates unique constraint "col2_unique"
DETAIL: Key (col2)=(2) already exists.
What the documentation says
conflict_target can perform unique index inference. When performing
inference, it consists of one or more index_column_name columns and/or
index_expression expressions, and an optional index_predicate. All
table_name unique indexes that, without regard to order, contain
exactly the conflict_target-specified columns/expressions are inferred
(chosen) as arbiter indexes. If an index_predicate is specified, it
must, as a further requirement for inference, satisfy arbiter indexes.
This gives the impression that the following query should work, but it does not because it would actually require a together unique index on col1 and col2. However such an index would not guarantee that col1 and col2 would be unique individually which is one of the OP's requirements.
INSERT INTO dupes values(3,2,'c')
ON CONFLICT (col1,col2) DO UPDATE SET col3 = 'c', col2 = 2
Let's call this query Q2 (this fails with a syntax error)
Why?
Postgresql behaves this way is because what should happen when a conflict occurs on the second column is not well defined. There are number of possibilities. For example in the above Q1 query, should postgresql update col1 when there is a conflict on col2? But what if that leads to another conflict on col1? how is postgresql expected to handle that?
A solution
A solution is to combine ON CONFLICT with old fashioned UPSERT.
CREATE OR REPLACE FUNCTION merge_db(key1 INT, key2 INT, data TEXT) RETURNS VOID AS
$$
BEGIN
LOOP
-- first try to update the key
UPDATE dupes SET col3 = data WHERE col1 = key1 and col2 = key2;
IF found THEN
RETURN;
END IF;
-- not there, so try to insert the key
-- if someone else inserts the same key concurrently, or key2
-- already exists in col2,
-- we could get a unique-key failure
BEGIN
INSERT INTO dupes VALUES (key1, key2, data) ON CONFLICT (col1) DO UPDATE SET col3 = data;
RETURN;
EXCEPTION WHEN unique_violation THEN
BEGIN
INSERT INTO dupes VALUES (key1, key2, data) ON CONFLICT (col2) DO UPDATE SET col3 = data;
RETURN;
EXCEPTION WHEN unique_violation THEN
-- Do nothing, and loop to try the UPDATE again.
END;
END;
END LOOP;
END;
$$
LANGUAGE plpgsql;
You would need to modify the logic of this stored function so that it updates the columns exactly the way you want it to. Invoke it like
SELECT merge_db(3,2,'c');
SELECT merge_db(1,2,'d');
In nowadays is (seems) impossible. Neither the last version of the ON CONFLICT syntax permits to repeat the clause, nor with CTE is possible: not is possible to breack the INSERT from ON CONFLICT to add more conflict-targets.
If you are using postgres 9.5, you can use the EXCLUDED space.
Example taken from What's new in PostgreSQL 9.5:
INSERT INTO user_logins (username, logins)
VALUES ('Naomi',1),('James',1)
ON CONFLICT (username)
DO UPDATE SET logins = user_logins.logins + EXCLUDED.logins;
Vlad got the right idea.
First you have to create a table unique constraint on the columns col1, col2 Then once you do that you can do the following:
INSERT INTO dupes values(3,2,'c')
ON CONFLICT ON CONSTRAINT dupes_pkey
DO UPDATE SET col3 = 'c', col2 = 2
ON CONFLICT ( col1, col2 )
DO UPDATE
SET
works fine. but you should not update col1, col2 in the SET section.
Create a constraint (foreign index, for example).
OR/AND
Look at existing constraints (\d in psq).
Use ON CONSTRAINT(constraint_name) in the INSERT clause.
You can typically (I would think) generate a statement with only one on conflict that specifies the one and only constraint that is of relevance, for the thing you are inserting.
Because typically, only one constraint is the "relevant" one, at a time. (If many, then I'm wondering if something is weird / oddly-designed, hmm.)
Example:
(License: Not CC0, only CC-By)
// there're these unique constraints:
// unique (site_id, people_id, page_id)
// unique (site_id, people_id, pages_in_whole_site)
// unique (site_id, people_id, pages_in_category_id)
// and only *one* of page-id, category-id, whole-site-true/false
// can be specified. So only one constraint is "active", at a time.
val thingColumnName = thingColumnName(notfificationPreference)
val insertStatement = s"""
insert into page_notf_prefs (
site_id,
people_id,
notf_level,
page_id,
pages_in_whole_site,
pages_in_category_id)
values (?, ?, ?, ?, ?, ?)
-- There can be only one on-conflict clause.
on conflict (site_id, people_id, $thingColumnName) <—— look
do update set
notf_level = excluded.notf_level
"""
val values = List(
siteId.asAnyRef,
notfPref.peopleId.asAnyRef,
notfPref.notfLevel.toInt.asAnyRef,
// Only one of these is non-null:
notfPref.pageId.orNullVarchar,
if (notfPref.wholeSite) true.asAnyRef else NullBoolean,
notfPref.pagesInCategoryId.orNullInt)
runUpdateSingleRow(insertStatement, values)
And:
private def thingColumnName(notfPref: PageNotfPref): String =
if (notfPref.pageId.isDefined)
"page_id"
else if (notfPref.pagesInCategoryId.isDefined)
"pages_in_category_id"
else if (notfPref.wholeSite)
"pages_in_whole_site"
else
die("TyE2ABK057")
The on conflict clause is dynamically generated, depending on what I'm trying to do. If I'm inserting a notification preference, for a page — then there can be a unique conflict, on the site_id, people_id, page_id constraint. And if I'm configuring notification prefs, for a category — then instead I know that the constraint that can get violated, is site_id, people_id, category_id.
So I can, and fairly likely you too, in your case?, generate the correct on conflict (... columns ), because I know what I want to do, and then I know which single one of the many unique constraints, is the one that can get violated.
Kind of hacky but I solved this by concatenating the two values from col1 and col2 into a new column, col3 (kind of like an index of the two) and compared against that. This only works if you need it to match BOTH col1 and col2.
INSERT INTO table
...
ON CONFLICT ( col3 )
DO UPDATE
SET
-- update needed columns here
Where col3 = the concatenation of the values from col1 and col2.
I get I am late to the party but for the people looking for answers I found this:
here
INSERT INTO tbl_Employee
VALUES (6,'Noor')
ON CONFLICT (EmpID,EmpName)
DO NOTHING;
ON CONFLICT is very clumsy solution, run
UPDATE dupes SET key1=$1, key2=$2 where key3=$3
if rowcount > 0
INSERT dupes (key1, key2, key3) values ($1,$2,$3);
works on Oracle, Postgres and all other database
I have a database table with a code column that uses a lowercase index to prevent code values that only differ in case (e.g. 'XYZ' = 'xYZ' = 'xyz'). The typical way in Postgresql is to create a function based index, like this: CREATE UNIQUE INDEX mytable_lower_code_idx ON mytable (lower(code)).
Now I have a case where I need upsert behaviour on that column:
-- first insert
INSERT INTO mytable (code) VALUES ('abcd');
-- second insert, with upsert behaviour
INSERT INTO mytable (code) VALUES ('Abcd')
ON CONFLICT (code) DO UPDATE
SET code='Abcd';
For the second insert I get a unique key violation: ERROR: duplicate key value violates unique constraint "mytable_lower_code_idx"
(I also tried to use ON CONFLICT ON CONSTRAINT mytable_lower_code_idx but Postgresql tells me that this constraint does not exist so maybe it doesn't treat the index as a constraint.)
My final question: Is there any way to make INSERT ... ON CONFLICT work together with indexes on expressions? Or must I introduce a physical indexed lowercase column to accomplish the task?
Use ON CONFLICT (lower(code)) DO UPDATE:
CREATE TABLE mytable (
code text
);
CREATE UNIQUE INDEX mytable_lower_code_idx ON mytable (lower(code));
INSERT INTO mytable VALUES ('abcd');
INSERT INTO mytable (code) VALUES ('Abcd')
ON CONFLICT (lower(code)) DO UPDATE
SET code='Abcd';
SELECT * FROM mytable;
yields
| code |
|------|
| Abcd |
Note that ON CONFLICT syntax
allows for the conflict target to be an index_expression (my emphasis):
ON CONFLICT conflict_target
where conflict_target can be one of:
( { index_column_name | ( index_expression ) } [ COLLATE collation ] [ opclass ] [, ...] ) [ WHERE index_predicate ]
ON CONSTRAINT constraint_name
and index_expression:
Similar to index_column_name, but used to infer expressions on
table_name columns appearing within index definitions (not simple
columns). Follows CREATE INDEX format.
Try to add your index as follow:
CREATE UNIQUE INDEX CONCURRENTLY mytable_lower_code_idx
ON mytable (lower(code));
ALTER TABLE mytable
ADD CONSTRAINT unique_mytab_code
UNIQUE USING INDEX mytable_lower_code_idx ;
and then:
INSERT INTO mytable (code) VALUES ('abcd');
-- second insert, with upsert behaviour
INSERT INTO mytable (code) VALUES ('Abcd')
ON CONFLICT ON CONSTRAINT unique_mytab_code DO UPDATE
SET code='Abcd';
I have two columns in table col1, col2, they both are unique indexed (col1 is unique and so is col2).
I need at insert into this table, use ON CONFLICT syntax and update other columns, but I can't use both column in conflict_targetclause.
It works:
INSERT INTO table
...
ON CONFLICT ( col1 )
DO UPDATE
SET
-- update needed columns here
But how to do this for several columns, something like this:
...
ON CONFLICT ( col1, col2 )
DO UPDATE
SET
....
ON CONFLICT requires a unique index* to do the conflict detection. So you just need to create a unique index on both columns:
t=# create table t (id integer, a text, b text);
CREATE TABLE
t=# create unique index idx_t_id_a on t (id, a);
CREATE INDEX
t=# insert into t values (1, 'a', 'foo');
INSERT 0 1
t=# insert into t values (1, 'a', 'bar') on conflict (id, a) do update set b = 'bar';
INSERT 0 1
t=# select * from t;
id | a | b
----+---+-----
1 | a | bar
* In addition to unique indexes, you can also use exclusion constraints. These are a bit more general than unique constraints. Suppose your table had columns for id and valid_time (and valid_time is a tsrange), and you wanted to allow duplicate ids, but not for overlapping time periods. A unique constraint won't help you, but with an exclusion constraint you can say "exclude new records if their id equals an old id and also their valid_time overlaps its valid_time."
A sample table and data
CREATE TABLE dupes(col1 int primary key, col2 int, col3 text,
CONSTRAINT col2_unique UNIQUE (col2)
);
INSERT INTO dupes values(1,1,'a'),(2,2,'b');
Reproducing the problem
INSERT INTO dupes values(3,2,'c')
ON CONFLICT (col1) DO UPDATE SET col3 = 'c', col2 = 2
Let's call this Q1. The result is
ERROR: duplicate key value violates unique constraint "col2_unique"
DETAIL: Key (col2)=(2) already exists.
What the documentation says
conflict_target can perform unique index inference. When performing
inference, it consists of one or more index_column_name columns and/or
index_expression expressions, and an optional index_predicate. All
table_name unique indexes that, without regard to order, contain
exactly the conflict_target-specified columns/expressions are inferred
(chosen) as arbiter indexes. If an index_predicate is specified, it
must, as a further requirement for inference, satisfy arbiter indexes.
This gives the impression that the following query should work, but it does not because it would actually require a together unique index on col1 and col2. However such an index would not guarantee that col1 and col2 would be unique individually which is one of the OP's requirements.
INSERT INTO dupes values(3,2,'c')
ON CONFLICT (col1,col2) DO UPDATE SET col3 = 'c', col2 = 2
Let's call this query Q2 (this fails with a syntax error)
Why?
Postgresql behaves this way is because what should happen when a conflict occurs on the second column is not well defined. There are number of possibilities. For example in the above Q1 query, should postgresql update col1 when there is a conflict on col2? But what if that leads to another conflict on col1? how is postgresql expected to handle that?
A solution
A solution is to combine ON CONFLICT with old fashioned UPSERT.
CREATE OR REPLACE FUNCTION merge_db(key1 INT, key2 INT, data TEXT) RETURNS VOID AS
$$
BEGIN
LOOP
-- first try to update the key
UPDATE dupes SET col3 = data WHERE col1 = key1 and col2 = key2;
IF found THEN
RETURN;
END IF;
-- not there, so try to insert the key
-- if someone else inserts the same key concurrently, or key2
-- already exists in col2,
-- we could get a unique-key failure
BEGIN
INSERT INTO dupes VALUES (key1, key2, data) ON CONFLICT (col1) DO UPDATE SET col3 = data;
RETURN;
EXCEPTION WHEN unique_violation THEN
BEGIN
INSERT INTO dupes VALUES (key1, key2, data) ON CONFLICT (col2) DO UPDATE SET col3 = data;
RETURN;
EXCEPTION WHEN unique_violation THEN
-- Do nothing, and loop to try the UPDATE again.
END;
END;
END LOOP;
END;
$$
LANGUAGE plpgsql;
You would need to modify the logic of this stored function so that it updates the columns exactly the way you want it to. Invoke it like
SELECT merge_db(3,2,'c');
SELECT merge_db(1,2,'d');
In nowadays is (seems) impossible. Neither the last version of the ON CONFLICT syntax permits to repeat the clause, nor with CTE is possible: not is possible to breack the INSERT from ON CONFLICT to add more conflict-targets.
If you are using postgres 9.5, you can use the EXCLUDED space.
Example taken from What's new in PostgreSQL 9.5:
INSERT INTO user_logins (username, logins)
VALUES ('Naomi',1),('James',1)
ON CONFLICT (username)
DO UPDATE SET logins = user_logins.logins + EXCLUDED.logins;
Vlad got the right idea.
First you have to create a table unique constraint on the columns col1, col2 Then once you do that you can do the following:
INSERT INTO dupes values(3,2,'c')
ON CONFLICT ON CONSTRAINT dupes_pkey
DO UPDATE SET col3 = 'c', col2 = 2
ON CONFLICT ( col1, col2 )
DO UPDATE
SET
works fine. but you should not update col1, col2 in the SET section.
Create a constraint (foreign index, for example).
OR/AND
Look at existing constraints (\d in psq).
Use ON CONSTRAINT(constraint_name) in the INSERT clause.
You can typically (I would think) generate a statement with only one on conflict that specifies the one and only constraint that is of relevance, for the thing you are inserting.
Because typically, only one constraint is the "relevant" one, at a time. (If many, then I'm wondering if something is weird / oddly-designed, hmm.)
Example:
(License: Not CC0, only CC-By)
// there're these unique constraints:
// unique (site_id, people_id, page_id)
// unique (site_id, people_id, pages_in_whole_site)
// unique (site_id, people_id, pages_in_category_id)
// and only *one* of page-id, category-id, whole-site-true/false
// can be specified. So only one constraint is "active", at a time.
val thingColumnName = thingColumnName(notfificationPreference)
val insertStatement = s"""
insert into page_notf_prefs (
site_id,
people_id,
notf_level,
page_id,
pages_in_whole_site,
pages_in_category_id)
values (?, ?, ?, ?, ?, ?)
-- There can be only one on-conflict clause.
on conflict (site_id, people_id, $thingColumnName) <—— look
do update set
notf_level = excluded.notf_level
"""
val values = List(
siteId.asAnyRef,
notfPref.peopleId.asAnyRef,
notfPref.notfLevel.toInt.asAnyRef,
// Only one of these is non-null:
notfPref.pageId.orNullVarchar,
if (notfPref.wholeSite) true.asAnyRef else NullBoolean,
notfPref.pagesInCategoryId.orNullInt)
runUpdateSingleRow(insertStatement, values)
And:
private def thingColumnName(notfPref: PageNotfPref): String =
if (notfPref.pageId.isDefined)
"page_id"
else if (notfPref.pagesInCategoryId.isDefined)
"pages_in_category_id"
else if (notfPref.wholeSite)
"pages_in_whole_site"
else
die("TyE2ABK057")
The on conflict clause is dynamically generated, depending on what I'm trying to do. If I'm inserting a notification preference, for a page — then there can be a unique conflict, on the site_id, people_id, page_id constraint. And if I'm configuring notification prefs, for a category — then instead I know that the constraint that can get violated, is site_id, people_id, category_id.
So I can, and fairly likely you too, in your case?, generate the correct on conflict (... columns ), because I know what I want to do, and then I know which single one of the many unique constraints, is the one that can get violated.
Kind of hacky but I solved this by concatenating the two values from col1 and col2 into a new column, col3 (kind of like an index of the two) and compared against that. This only works if you need it to match BOTH col1 and col2.
INSERT INTO table
...
ON CONFLICT ( col3 )
DO UPDATE
SET
-- update needed columns here
Where col3 = the concatenation of the values from col1 and col2.
I get I am late to the party but for the people looking for answers I found this:
here
INSERT INTO tbl_Employee
VALUES (6,'Noor')
ON CONFLICT (EmpID,EmpName)
DO NOTHING;
ON CONFLICT is very clumsy solution, run
UPDATE dupes SET key1=$1, key2=$2 where key3=$3
if rowcount > 0
INSERT dupes (key1, key2, key3) values ($1,$2,$3);
works on Oracle, Postgres and all other database