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How to get the index of an element in an IEnumerable?
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extensions with overloads like Select((x, i) => ...) seem to imply that these indexes should exist
– Michael
Mar 19 '14 at 16:05
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Computed / calculated / virtual / derived columns in PostgreSQL
...y as column?
The expression (looking like a column) is not included in a SELECT * FROM tbl, though. You always have to list it explicitly.
Can also be supported with a matching expression index - provided the function is IMMUTABLE. Like:
CREATE FUNCTION col(tbl) ... AS ... -- your computed expr...
How do I drop a foreign key constraint only if it exists in sql server?
...target a foreign key constraint on a specific table, use this:
IF EXISTS (SELECT *
FROM sys.foreign_keys
WHERE object_id = OBJECT_ID(N'dbo.FK_TableName_TableName2')
AND parent_object_id = OBJECT_ID(N'dbo.TableName')
)
ALTER TABLE [dbo.TableName] DROP CONSTRAINT [FK_TableName_TableName2]...
Why is setTimeout(fn, 0) sometimes useful?
... recently run into a rather nasty bug, wherein the code was loading a <select> dynamically via JavaScript. This dynamically loaded <select> had a pre-selected value. In IE6, we already had code to fix the selected <option> , because sometimes the <select> 's selected...
What is the benefit of zerofill in MySQL?
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When you select a column with type ZEROFILL it pads the displayed value of the field with zeros up to the display width specified in the column definition. Values longer than the display width are not truncated. Note that usage of ZER...
Possible to do a MySQL foreign key to one of two possible tables?
...ecific type of filter is easy if you know which type you want to join to:
SELECT * FROM Products
INNER JOIN FiltersType2 USING (product_id)
If you want the filter type to be dynamic, you must write application code to construct the SQL query. SQL requires that the table be specified and fixed at ...
SQL Query to concatenate column values from multiple rows in Oracle
...on on string aggregation techniques. A very common one is to use LISTAGG:
SELECT pid, LISTAGG(Desc, ' ') WITHIN GROUP (ORDER BY seq) AS description
FROM B GROUP BY pid;
Then join to A to pick out the pids you want.
Note: Out of the box, LISTAGG only works correctly with VARCHAR2 columns.
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How to get the mysql table columns data type?
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You can use the information_schema columns table:
SELECT DATA_TYPE FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'tbl_name' AND COLUMN_NAME = 'col_name';
share
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im...
SQL Server - Create a copy of a database table and place it in the same database?
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Use SELECT ... INTO:
SELECT *
INTO ABC_1
FROM ABC;
This will create a new table ABC_1 that has the same column structure as ABC and contains the same data. Constraints (e.g. keys, default values), however, are -not- copied.
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How do you truncate all tables in a database using TSQL?
...'
EXEC sp_MSforeachtable 'SET QUOTED_IDENTIFIER ON';
IF NOT EXISTS (
SELECT
*
FROM
SYS.IDENTITY_COLUMNS
JOIN SYS.TABLES ON SYS.IDENTITY_COLUMNS.Object_ID = SYS.TABLES.Object_ID
WHERE
SYS.TABLES.Object_ID = OBJECT_ID('?') AND SYS.IDENTITY_COLUMNS.Last_Val...