I have a table af with columns af.id, etc. and a table af_pb with columns af_id and pb_id (which assigns entities from table pb to the entities of table af).
What i want:
add a new column precedence in table af
for each af.id in af:
if there is a pair (af_id, pb_id) with af.id = af_id and some pb_id in the join table af_pb, then set af.precedence = 0
if there is no such pair, set af.precedence = 1
How can i reach this in PostgreSQL? I already read about the case-when-else-statement but I didn't managed to implement it such that the column precedence is set correctly.
While this can be done in with a case expression, it is not necessary. If you want a default value for later inserts into table af then alter the table with it, then update to set the non-default.
alter table af add column precedence integer default 1;
update af
set precedence = 0
where exists (select null
from af_pb
where af.af_id = af_pb.af_id);
If a default is not desired then a just add the column and afterward update to set the appropriate value:
alter table af add column precedence integer;
update af
set precedence =
( not (exists (select null
from af_pb
where af.af_id = af_pb.af_id)))::integer;
I have a column on my table called RecordId. I want to duplicate this column to a column named BookId. I know I can add column like this:
ALTER TABLE products ADD COLUMN BookId;
But how do I populate the value from the other column?
UPDATE products
SET BookId = RecordId
WHERE RecordId > 0
I want to update a table with postgresql.
In fact, I have a table (TABLE_ONE) with two column (old_id and new_id). I have a second table (TABLE_TWO) with colums (id,column1,column2,...).
I want to update the column id from TABLE_TWO. The wanted behavior is that when TABLE_ONE.id = TABLE_TWO.old_id, we set id to new_id.
How can i do that?
You want an UPDATE FROM statement:
UPDATE table_one
SET table_one.id = table_two.id
FROM table_two
WHERE table_one.id = table_two.old_id;
I've got two tables that I'd like to combine into a view. The first table contains the structure:
Template Table
componentID | title
======================
1000 | blue
1001 | red
1002 | orange
The second table contains the actual data that will be stored, and the columns reference the ID of the first table:
Data Table
id | field1000 | field1001 | field1002
======================================
1 | navy | ruby | vermilion
2 | midnight | crimson | amber
What I'd like to get as a result in a view:
Combined Table/View?
id | blue | red | orange
=================================
1 | navy | ruby | vermilion
2 | midnight | crimson | amber
Is this possible? I've been trying to get it to work with pivot tables, but I'm getting hung up on how to use the titles as the columns for the data.
Ok, I went a bit overboard with this one but this will do what you want. This procedure will combine all fields with the proper data table columns, and does not need to know nor care how many columns there are in the data tables.
It does not use cursors, but due to the possibility of many template tables, it does use Dynamic SQL to generate the Select statement for the final return.
Only caveat is it's not a View, it's a stored procedure, because it allows to pass the variable for the data table you want to ultimately select from.
The assumptions:
The template table is static
There is one template table for all data tables
All fields in any data tables must be unique *
All data tables have a PK/identity field with the word 'id' in it that must be ignored
All fields in the data tables have a corresponding title in the template table
All fields in the data table are prefixed with the word 'field' and all of the reference ID's in the template table correspond to those field names with 'field' removed, based on your example
*- It can of course be improved by modifying the template table schema to also have a field for the data table that the field title belongs to, for example, which would remove this assumption #3.
The process:
First we need a mapping of the field names, reference IDs, and column titles. We do this with a table variable and get our info from syscolumns. Then, we update our temp table to get the titles from the TemplateTable table.
Then, we need to build a dynamic Select list from the DataTable (which is a parameter in the SP and therefore requires some dynamic SQL to execute). My preferred method of doing this is by having a bit column in my source table that I can update, something like 'IsCompleted', and then using a regular While loop to get through each row. Inside the While loop, all we do is grab the current "TitleReference" from our temporary table variable, and append to the select list the real field name from syscolumns (from first step above).
Finally, we execute the dynamic SQL statement which has a Select, and when this is inside a stored procedure that is executed, the result is returned as the result of the stored procedure.
The Full Working Code
Create Procedure usp_CombineTables
(
#DataTableName varchar(50)
)
As
-- Test
-- Exec usp_CombineTables 'DataTable'
-- Set up our variables
Declare #DataTableIdFieldName varchar(50), -- The ID field of the data table, dynamic
#IsCompleted bit, -- Used by While loop to know when to exit
#CurrentTitleReference int, -- Used in While loop as the ID from TemplateTable that relates to the real data field name and the desired title
#CurrentDataFieldName varchar(50), -- Used in While loop for the current actual field name in the data table
#CurrentTitle varchar(50), -- Used in While loop for the desired field name in the resulting table of the stored proc
#DynamicSelectQuery varchar(2000) -- Stores the SQL query that is dynamically built and executed for the final result; can increase value if needed
-- Use table variable to correlate the datatable columns, titles, and references
Declare #TitleReferences Table (
TitleReference int,
DataTableColumnName varchar(50),
Title varchar(50),
Completed bit default 0
)
-- Get the info from syscolumns about our datatable; assumes that all of the field names are prefixed with the word 'field' which needs to be removed
Insert Into #TitleReferences (
TitleReference,
DataTableColumnName
)
Select
Replace(name, 'field', '') As TitleReference,
name As DataTableColumnName
From syscolumns
Where id = OBJECT_ID(#DataTableName)
And name Not Like '%id%' -- assumes DataTable will always have a PK with 'id' in it, need to ignore/remove
-- Get the titles -- assumes only one template table for all data tables; all data fields accross tables must be unique
Update #TitleReferences
Set Title = t.Title From TemplateTable As t
Where TitleReference = t.ComponentID
-- Get the ID field of the data table
Set #DataTableIdFieldName = (
Select name From syscolumns
Where id = OBJECT_ID(#DataTableName)
And name Like '%id%')
-- Build a dynamic SQL query to select from the datatable with the right column names
Set #DynamicSelectQuery = 'Select ' + #DataTableIdFieldName + ', ' -- start with the ID
Set #IsCompleted = 0
While (#IsCompleted = 0)
Begin
-- Retrieve the field name and title from the current row based on title reference
Set #CurrentTitleReference = (Select Top 1 TitleReference From #TitleReferences Where Completed = 0)
Set #CurrentDataFieldName = (Select DataTableColumnName From #TitleReferences Where TitleReference = #CurrentTitleReference)
Set #CurrentTitle = (Select Title From #TitleReferences Where TitleReference = #CurrentTitleReference)
-- Append the next select field to the dynamic query
Set #DynamicSelectQuery = #DynamicSelectQuery +
#CurrentDataFieldName + ' As ' + QuoteName(#CurrentTitle)
-- Set up to move past current record in next iteration
Update #TitleReferences Set Completed = 1 Where TitleReference = #CurrentTitleReference
-- Exit loop or add comma for next field
If (Select Count(Completed) From #TitleReferences Where Completed = 0) = 0
Begin
Set #IsCompleted = 1
End
Else
Begin
-- Add comma to select field for next column
Set #DynamicSelectQuery = #DynamicSelectQuery + ','
End
End
-- Now the column list is built, just add the table and exec
Set #DynamicSelectQuery = #DynamicSelectQuery +
' From ' + #DataTableName
Exec(#DynamicSelectQuery)
The Result
Hope this helps, it was fun writing it!
something on these lines
DECLARE #f0 VARCHAR(50)=(SELECT title FROM template WHERE componentID=1000)
DECLARE #f1 VARCHAR(50)=(SELECT title FROM template WHERE componentID=1001)
DECLARE #f2 VARCHAR(50)=(SELECT title FROM template WHERE componentID=1002)
#sql='SELECT field1000 AS ' + quotename(#f0) + ' field1001 AS ' + quotename(#f1) + ' field1002 AS ' + quotename(#f2) + ' FROM data'
exec sp_executesql #sql
After truncating table, and inserting new values in table, auto-increment values are not set to started value 1. When inserting new values it's remember last index-ed value of auto-increment.
Colum in table named: ID
Index: PRIMARY,
Initial Value: 1
Cache size: 1
Increment: 1
[checked on IBM DB2 Control Center]
This query:
TRUNCATE TABLE ".$this->_schema.$table." DROP STORAGE IGNORE DELETE TRIGGERS IMMEDIATE
table is EMPTY.
After INSERT NEW VALUES example: INSERT INTO DB2INST1.db (val) VALUES ('abc') it's INSERT with LAST
ID | val
55 | abc
But it SHOULD BE:
ID | val
1 | abc
I'm guessing here that your question is "how do you restart the IDENTITY sequence?" If that is the case, then you can reset it with the following SQL:
ALTER TABLE <table name> ALTER COLUMN <IDENTITY column> RESTART WITH 1
However, like #Ian said, what you are seeing is the expected behavior of a TRUNCATE.
First select in TABLE SCHEMA WHERE is name of IDENTITY column:
Query 1:
SELECT COLNAME FROM SYSCAT.COLUMNS WHERE TABSCHEMA = 'DB2INST1' AND
TABNAME = 'DB' AND IDENTITY = 'Y'
Then, truncate table and return it's example: ID for altering index:
Query 2:
This ID puts on query for reset and altering index identity:
ALTER TABLE DB2INST1.DB ALTER COLUMN ID RESTART WITH 1
Change ID above returned from Query 1, which returns name of ID to Query 2.
SOLVED!