I need to duplicate one line of a specific table, but in same duplicated line I have to change the primary key. In my case the primary key is a three digit year. Example: this year would be 221, next year 222.
I'm using a record with a primary key of 999 that I'll duplicate. Now I need to make it dynamic (doesn't has to be dynamic while testing), so that I can use it for more than one table only, because it will be called from a procedure in RPGLE.
I've used a very static method for that before:
INSERT INTO Table
SELECT PK -- the PK is the new year, in this case 222 and all other fields are added as well.
FROM Table
WHERE PK = 999;
And I have tried to get something like that (I know that this is not working):
INSERT INTO Table WHERE PK = 222
SELECT * FROM Table WHERE PK = 999;
I hope this is enough information to understand what I would like to achieve and that its possible to do so.
Thanks in advance
If you used tables you don't have to name columns.
So you can build dynamic statements and execute immediate :
declare global temporary table copyrows as (
select * from table1 where pk = 999
) with data with replace;
update session.copyrows set pk = 222;
insert into table1 select * from session.copyrows;
Related
Let's say I have 2 tables: Students and Groups.
The Group table has 2 columns: id, GroupName
The Student table has 3 columns: id, StudentName and GroupID
The GroupID is a foreign key to a Group field.
I need to import the Students table from a CSV, but in my CSV instead of the Group id appears the name of the group. How can I import it with pgAdmin without modifying the csv?
Based on Laurenz answer, use follwoing scripts:
Create a temp table to insert from CSV file:
CREATE TEMP TABLE std_temp (id int, student_name char(25), group_name char(25));
Then, import the CSV file:
COPY std_temp FROM '/home/username/Documents/std.csv' CSV HEADER;
Now, create std and grp tables for students and groups:
CREATE TABLE grp (id int, name char(25));
CREATE TABLE std (id int, name char(20), grp_id int);
It's grp table's turn to be populated based on distinct value of group name. Consider how row_number() is use to provide value for id`:
INSERT INTO grp (id, name) select row_number() OVER (), * from (select distinct group_name from std_temp) as foo;
And the final step, select data based on the join then insert it into the std table:
insert into std (id, name, grp_id) select std_temp.id, std_temp.student_name,grp.id from std_temp inner join grp on std_temp.group_name = grp.name;
At the end, retreive data from final std table:
select * from std;
Your easiest option is to import the file into a temporary table that is defined like the CSV file. Then you can join that table with the "groups" table and use INSERT INTO ... SELECT ... to populate the "students" table.
There is of course also the option to define a view on a join of the two tables and define an INSTEAD OF INSERT trigger on the view that inserts values into the underlying tables as appropriate. Then you could load the data directly to the view.
The suggestion by #LaurenzAlbe is the obvious approach (IMHO never load a spreadsheet directly to
your tables, they are untrustworthy beasts). But I believe your implementation after loading the staging
table is flawed.
First, using row_number() virtually ensures you get duplicated ids for the same group name.
The ids will always increment from 1 by 1 to then number of group names no matter the number of groups previously loaded and you cannot ensure the identical sequence on a subsequent spreadsheets. What happens when you have a group that does not previously exist.
Further there is no validation that the group name does not already exist. Result: Duplicate group names and/or multiple ids for the same name.
Second, you attempt to use the id from the spreadsheet as the id the student (std) table is full of error possibilities. How do you ensure that number is unique across spreadsheets?
Even if unique in a single spreadsheet, how do you ensure another spreadsheet does not use the same numbers as a previous one. Or assuming multiple users create the spreadsheets that one users numbers do not overlap another users even if all users
user are very conscious of the numbers they use. Result: Duplicate id numbers.
A much better approach would be to put a unique key on the group table name column then insert any group names from the stage table into the group trapping any duplicate name errors (using on conflict). Then load the student table directly from the stage table
while selecting group id from the group table by the (now unique) group name.
create table csv_load_temp( junk_num integer, student_name text, group_name text);
create table groups( grp_id integer generated always as identity
, name text
, grp_key text generated always as ( lower(name) ) stored
, constraint grp_pk
primary key (grp_id)
, constraint grp_bk
unique (grp_key)
);
create table students (std_id integer generated always as identity
, name text
, grp_id integer
, constraint std_pk
primary key (std_id)
, constraint std2grp_fk
foreign key (grp_id)
references groups(grp_id)
);
-- Function to load Groups and Students
create or replace function establish_students()
returns void
language sql
as $$
insert into groups (name)
select distinct group_name
from csv_load_temp
on conflict (grp_key) do nothing;
insert into students (name, grp_id)
select student_name, grp_id
from csv_load_temp t
join groups grp
on (grp.name = t.group_name);
$$;
The groups table requires Postgres v12. For prior versions remove the column grp_key couumn
and and put the unique constraint directly on the name column. What to do about capitalization is up to your business logic.
See fiddle for full example. Obviously the 2 inserts in the Establish_Students function can be run standalone and independently. In that case the function itself is not necessary.
I have two tables lets say table1 with id, fname, lname, gender and table2 with fname, lname.
table2 contains some data. I want to select all the data from table2 that has lname as "roy" and insert into table one incrementing value of id. But I don't want to use triggers. Is there anyway to do this.
If you have auto incrementing column id then just omit it while performing an insert and let the database get next value from sequence and assign it to a newly inserted record:
INSERT INTO table1 (fname, lname)
SELECT fname, lname
FROM table2
WHERE fname = 'roy'
If you don't have one, then you should probably create it, or use the last value + 1 (not safe and not recommended).
In different databases creating an auto incrementing column is done differently:
PostgreSQL has SERIAL
SQL Server has IDENTITY
Oracle pre 12c has sequences and triggers and PL/SQL triggers
I have a Microsoft SQL Server database with a table called tblCABLE with the following two relevant columns:
ID - indentity
CableID - nchar(8) not null
I have an After Insert trigger on that table that I have written and when all the columns of tblCABLE are entered it runs fine on.
I am trying to create a front end form in access for data entry to tblCABLE so that the trigger can run on new rows.
My problem is that I want the column of CableID to be populated automatically on opening a new record form in Access but do not know how to do this.
I have written some SQL code which will generate the new CableID as follows (the problem is how to add this to run on a new record form in Access
declare #newcableID nchar(8)
declare #cableIDnum int
declare #maxcableID nchar(8)
set #maxcableID = (select max(cableid) from tblCable)
set #cableIDnum = (convert(int, substring(#maxcableID,3,8)))
set #cableIDnum = #cableIDnum + 1
set #newcableID = (select 'CA' + right('000000' + cast((#cableIDnum) as varchar),6))
Any help would be greatly appreciated.
Please don't do this! Using a SELECT MAX()+1 approach is inherently bad and it will break under load and produce duplicate values.
Let the SQL Server database handle this by using a column of type INT IDENTITY - something like:
CREATE TABLE dbo.tblCable
(ID INT IDENTITY(1, 1) NOT NULL
CONSTRAINT PK_tblCable PRIMARY KEY CLUSTERED,
...(other columns here).....
)
That way, SQL Server guarantees properly handled ID values - once you've inserted a new row, the ID will be a unique, valid number and you don't have to fiddle and mess around with creating that unique ID yourself.
If you need a column that concatenates the numeric ID value with a fixed prefix, use a computed column:
ALTER TABLE dbo.tblCable
ADD CableID AS 'CA' + RIGHT('000000' + CAST(ID AS VARCHAR(6)), 6) PERSISTED
and you're done! Whenever you insert a new row, SQL Server will give you a unique ID (e.g. 42), and your CableID column will automatically contain CA000042
I've never had to post a question on StackOverflow before because I can always find an answer here by just searching. Only this time, I think I've got a real stumper....
I'm writing code that automates the process of moving data from one SQL Server database to another. I have some pretty standard SQL Server Databases with foreign key relationships between some of their tables. Straight forward stuff. One of my requirements is that the entire table needs to be copied in one fell swoop, without looping through rows or using a cursor. Another requirement is I have to do this in SQL, no SSIS or other external helpers.
For example:
INSERT INTO TargetDatabase.dbo.MasterTable
SELECT * FROM SourceDatabase.dbo.MasterTable
That's easy enough. Then, once the data from the MasterTable has been moved, I move the data of the child table.
INSERT INTO TargetDatabase.dbo.ChildTable
SELECT * FROM SourceDatabase.dbo.ChildTable
Of course, in reality I use more explicit SQL... like I specifically name all the fields and things like that, but this is just a simplified version. Anyway, so far everything's going alright, except ...
The problem is that the primary key of the master table is defined as an identity field. So, when I insert into the MasterTable, the primary key for the new table gets calculated by the database. So to deal with that, I tried using the OUTPUT INTO statement to get the updated values into a Temp table:
INSERT INTO TargetDatabase.dbo.MasterTable
OUPUT INSERTED.* INTO #MyTempTable
SELECT * FROM SourceDatabase.dbo.MasterTable
So here's where it all falls apart. Since the database changed the primary key, how on earth do I figure out which record in the temp table matches up with the original record in the source table?
Do you see the problem? I know what the new ID is, I just don't know how to match it with the original record reliably. The SQL server lets me output the INSERTED values, but doesn't let me output the FROM TABLE values along side the INSERTED values. I've tried it with triggers, I've tried it with an SP, always I have the same problem.
If I were just updating one record at a time, I could easily match up my INSERTED values with the original record I was trying to insert to see the old and new primary key values, but I have this requirement to do it in a batch.
Any Ideas?
PS: I'm not allowed to change the table structure of the target or source table.
You can use MERGE.
declare #Source table (SourceID int identity(1,2), SourceName varchar(50))
declare #Target table (TargetID int identity(2,2), TargetName varchar(50))
insert into #Source values ('Row 1'), ('Row 2')
merge #Target as T
using #Source as S
on 0=1
when not matched then
insert (TargetName) values (SourceName)
output inserted.TargetID, S.SourceID;
Result:
TargetID SourceID
----------- -----------
2 1
4 3
Covered in this blog post by Adam Machanic: Dr. OUTPUT or: How I Learned to Stop Worrying and Love the MERGE
To illustrate what I mentioned in the comment:
SET IDENTITY_INSERT TargetDatabase.dbo.MasterTable ON
INSERT INTO TargetDatabase.dbo.MasterTable (IdentityColumn, OtherColumn1, OtherColumn2, ...)
SELECT IdentityColumn, OtherColumn1, OtherColumn2, ...
FROM SourceDatabase.dbo.MasterTable
SET IDENTITY_INSERT TargetDatabase.dbo.MasterTable OFF
Okay, since that didn't work for you (pre-existing values in target tables), how about adding a fixed increment (offset) to the id values in both tables (use the current max id value). Assuming the identity column is "id" in both tables:
DECLARE #incr int
BEGIN TRAN
SELECT #incr = max(id)
FROM TargetDatabase.dbo.MasterTable AS m WITH (TABLOCKX, HOLDLOCK)
SET IDENTITY_INSERT TargetDatabase.dbo.MasterTable ON
INSERT INTO TargetDatabase.dbo.MasterTable (id{, othercolumns...})
SELECT id+#incr{, othercolumns...}
FROM SourceDatabase.dbo.MasterTable
SET IDENTITY_INSERT TargetDatabase.dbo.MasterTable OFF
INSERT INTO TargetDatabase.dbo.ChildTable (id{, othercolumns...})
SELECT id+#incr{, othercolumns...}
FROM SourceDatabase.dbo.ChildTable
COMMIT TRAN
I need to duplicate selected rows with all the fields exactly same except ID ident int which is added automatically by SQL.
What is the best way to duplicate/clone record or records (up to 50)?
Is there any T-SQL functionality in MS SQL 2008 or do I need to select insert in stored procedures ?
The only way to accomplish what you want is by using Insert statements which enumerate every column except the identity column.
You can of course select multiple rows to be duplicated by using a Select statement in your Insert statements. However, I would assume that this will violate your business key (your other unique constraint on the table other than the surrogate key which you have right?) and require some other column to be altered as well.
Insert MyTable( ...
Select ...
From MyTable
Where ....
If it is a pure copy (minus the ID field) then the following will work (replace 'NameOfExistingTable' with the table you want to duplicate the rows from and optionally use the Where clause to limit the data that you wish to duplicate):
SELECT *
INTO #TempImportRowsTable
FROM (
SELECT *
FROM [NameOfExistingTable]
-- WHERE ID = 1
) AS createTable
-- If needed make other alterations to the temp table here
ALTER TABLE #TempImportRowsTable DROP COLUMN Id
INSERT INTO [NameOfExistingTable]
SELECT * FROM #TempImportRowsTable
DROP TABLE #TempImportRowsTable
If you're able to check the duplication condition as rows are inserted, you could put an INSERT trigger on the table. This would allow you to check the columns as they are inserted instead of having to select over the entire table.