问题
I need to add a specific column if it does not exist. I have something like the following, but it always returns false:
IF EXISTS(SELECT *
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = \'myTableName\'
AND COLUMN_NAME = \'myColumnName\')
How can I check if a column exists in a table of the SQL Server database?
回答1:
SQL Server 2005 onwards:
IF EXISTS(SELECT 1 FROM sys.columns
WHERE Name = N'columnName'
AND Object_ID = Object_ID(N'schemaName.tableName'))
BEGIN
-- Column Exists
END
Martin Smith's version is shorter:
IF COL_LENGTH('schemaName.tableName', 'columnName') IS NOT NULL
BEGIN
-- Column Exists
END
回答2:
A more concise version
IF COL_LENGTH('table_name','column_name') IS NULL
BEGIN
/* Column does not exist or caller does not have permission to view the object */
END
The point about permissions on viewing metadata applies to all answers not just this one.
Note that the first parameter table name to COL_LENGTH can be in one, two, or three part name format as required.
An example referencing a table in a different database is
COL_LENGTH('AdventureWorks2012.HumanResources.Department','ModifiedDate')
One difference with this answer compared to using the metadata views is that metadata functions such as COL_LENGTH always only return data about committed changes irrespective of the isolation level in effect.
回答3:
Tweak the below to suit your specific requirements:
if not exists (select
column_name
from
INFORMATION_SCHEMA.columns
where
table_name = 'MyTable'
and column_name = 'MyColumn')
alter table MyTable add MyColumn int
Edit to deal with edit to question: That should work - take a careful look over your code for stupid mistakes; are you querying INFORMATION_SCHEMA on the same database as your insert is being applied to for example? Do you have a typo in your table/column name in either statement?
回答4:
Try this...
IF NOT EXISTS(
SELECT TOP 1 1
FROM INFORMATION_SCHEMA.COLUMNS
WHERE
[TABLE_NAME] = 'Employees'
AND [COLUMN_NAME] = 'EmployeeID')
BEGIN
ALTER TABLE [Employees]
ADD [EmployeeID] INT NULL
END
回答5:
I'd prefer INFORMATION_SCHEMA.COLUMNS over a system table because Microsoft does not guarantee to preserve the system tables between versions. For example, dbo.syscolumns does still work in SQL 2008, but it's deprecated and could be removed at any time in future.
回答6:
You can use the information schema system views to find out pretty much anything about the tables you're interested in:
SELECT *
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'yourTableName'
ORDER BY ORDINAL_POSITION
You can also interrogate views, stored procedures and pretty much anything about the database using the Information_schema views.
回答7:
For the people who is checking the column existence to drop it.
From SQL Server 2016 you can use new DIE statements instead of big IF wrappers
ALTER TABLE Table_name DROP COLUMN IF EXISTS Column_name
回答8:
First check if the table/column(id/name) combination exists in dbo.syscolumns (an internal SQL Server table that contains field definitions), and if not issue the appropriate ALTER TABLE query to add it. For example:
IF NOT EXISTS ( SELECT *
FROM syscolumns
WHERE id = OBJECT_ID('Client')
AND name = 'Name' )
ALTER TABLE Client
ADD Name VARCHAR(64) NULL
回答9:
Try something like:
CREATE FUNCTION ColumnExists(@TableName varchar(100), @ColumnName varchar(100))
RETURNS varchar(1) AS
BEGIN
DECLARE @Result varchar(1);
IF EXISTS (SELECT * FROM INFORMATION_SCHEMA.Columns WHERE TABLE_NAME = @TableName AND COLUMN_NAME = @ColumnName)
BEGIN
SET @Result = 'T'
END
ELSE
BEGIN
SET @Result = 'F'
END
RETURN @Result;
END
GO
GRANT EXECUTE ON [ColumnExists] TO [whoever]
GO
Then use it like this:
IF ColumnExists('xxx', 'yyyy') = 'F'
BEGIN
ALTER TABLE xxx
ADD yyyyy varChar(10) NOT NULL
END
GO
It should work on both SQL Server 2000 & SQL Server 2005. Not sure about SQL Server 2008, but don't see why not.
回答10:
A good friend and colleague of mine showed me how you can also use an IF block with SQL functions OBJECT_ID and COLUMNPROPERTY in SQL SERVER 2005+ to check for a column. You can use something similar to the following:
You can see for yourself here
IF (OBJECT_ID(N'[dbo].[myTable]') IS NOT NULL AND
COLUMNPROPERTY( OBJECT_ID(N'[dbo].[myTable]'), 'ThisColumnDoesNotExist', 'ColumnId') IS NULL)
BEGIN
SELECT 'Column does not exist -- You can add TSQL to add the column here'
END
回答11:
declare @myColumn as nvarchar(128)
set @myColumn = 'myColumn'
if not exists (
select 1
from information_schema.columns columns
where columns.table_catalog = 'myDatabase'
and columns.table_schema = 'mySchema'
and columns.table_name = 'myTable'
and columns.column_name = @myColumn
)
begin
exec('alter table myDatabase.mySchema.myTable add'
+' ['+@myColumn+'] bigint null')
end
回答12:
Try this
SELECT COLUMNS.*
FROM INFORMATION_SCHEMA.COLUMNS COLUMNS,
INFORMATION_SCHEMA.TABLES TABLES
WHERE COLUMNS.TABLE_NAME = TABLES.TABLE_NAME
AND Upper(COLUMNS.COLUMN_NAME) = Upper('column_name')
回答13:
This worked for me in SQL 2000:
IF EXISTS
(
SELECT *
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'table_name'
AND column_name = 'column_name'
)
BEGIN
...
END
回答14:
I needed similar for SQL SERVER 2000 and, as @Mitch points out, this only works inm 2005+.
Should it help anyone else, this is what worked for me in the end:
if exists (
select *
from
sysobjects, syscolumns
where
sysobjects.id = syscolumns.id
and sysobjects.name = 'table'
and syscolumns.name = 'column')
回答15:
if exists (
select *
from INFORMATION_SCHEMA.COLUMNS
where TABLE_NAME = '<table_name>'
and COLUMN_NAME = '<column_name>'
) begin
print 'Column you have specified exists'
end else begin
print 'Column does not exist'
end
回答16:
IF NOT EXISTS( SELECT NULL
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'TableName'
AND table_schema = 'SchemaName'
AND column_name = 'ColumnName') BEGIN
ALTER TABLE [SchemaName].[TableName] ADD [ColumnName] int(1) NOT NULL default '0';
END;
回答17:
select distinct object_name(sc.id)
from syscolumns sc,sysobjects so
where sc.name like '%col_name%' and so.type='U'
回答18:
A temp table version of the accepted answer:
if (exists(select 1
from tempdb.sys.columns
where Name = 'columnName'
and Object_ID = object_id('tempdb..#tableName')))
begin
...
end
回答19:
Wheat's answer is good, but assumes you do not have any identical table name / column name pairs in any schema or database. To make it safe for that condition use this...
select *
from Information_Schema.Columns
where Table_Catalog = 'DatabaseName'
and Table_Schema = 'SchemaName'
and Table_Name = 'TableName'
and Column_Name = 'ColumnName'
回答20:
There are several ways to check the existence of a column.
I would strongly recommend to use INFORMATION_SCHEMA.COLUMNS as it is created in order to communicate with user.
Consider following tables:
sys.objects
sys.columns
and even some other access methods available to check system catalog.
Also, no need to use SELECT *, simply test it by NULL value
IF EXISTS(
SELECT NULL
FROM INFORMATION_SCHEMA.COLUMNS
WHERE
TABLE_NAME = 'myTableName'
AND COLUMN_NAME = 'myColumnName'
)
回答21:
One of the most simple and understandable solution is:
IF COL_LENGTH('Table_Name','Column_Name') IS NULL
BEGIN
-- Column Not Exists, implement your logic
END
ELSE
BEGIN
-- Column Exists, implement your logic
END
回答22:
Here is a simple script I use to manage addition of columns in the database:
IF NOT EXISTS (
SELECT *
FROM sys.Columns
WHERE Name = N'QbId'
AND Object_Id = Object_Id(N'Driver')
)
BEGIN
ALTER TABLE Driver ADD QbId NVARCHAR(20) NULL
END
ELSE
BEGIN
PRINT 'QbId is already added on Driver'
END
In this example, the Name is the ColumnName to be added and Object_Id is the TableName
回答23:
Below query can be used to check whether searched column exists or not in the table. We can take decision based on the searched result also as shown below.
IF EXISTS (SELECT 'Y' FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = <YourTableName> AND COLUMN_NAME = <YourColumnName>)
BEGIN
SELECT 'Column Already Exists.'
END
ELSE
BEGIN
ALTER TABLE <YourTableName> ADD <YourColumnName> <DataType>[Size]
END
回答24:
Yet another variation...
SELECT
Count(*) AS existFlag
FROM
sys.columns
WHERE
[name] = N 'ColumnName'
AND [object_id] = OBJECT_ID(N 'TableName')
回答25:
table -->script table as -->new windows - you have design script. check and find column name in new windows
回答26:
Execute the below query to check if the column exists in the given table:
IF(SELECT COLUMN_NAME from INFORMATION_SCHEMA.COLUMNS where TABLE_NAME = 'TableName' AND COLUMN_NAME = 'ColumnName') IS NOT NULL
PRINT 'Column Exists in the given table';
回答27:
IF EXISTS(SELECT 1 FROM sys.columns
WHERE Name = N'columnName'
AND Object_ID = Object_ID(N'schemaName.tableName'))
This should be the fairly easier way and straight forward solution to this problem. I have used this multiple times for similar scenarios. It works like a charm, no doubts on that.
回答28:
IF EXISTS (
SELECT *
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_CATALOG = 'Database Name'
and TABLE_SCHEMA = 'Schema Name'
and TABLE_NAME = 'Table Name'
and COLUMN_NAME = 'Column Name'
and DATA_TYPE = 'Column Type') -- Where statement lines can be deleted.
BEGIN
--COLUMN EXISTS IN TABLE
END
ELSE BEGIN
--COLUMN DOES NOT EXISTS IN TABLE
END
回答29:
Another contribute is the following sample that add the column if not exist.
USE [Northwind]
GO
IF NOT EXISTS(SELECT * FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'Categories'
AND COLUMN_NAME = 'Note')
BEGIN
ALTER TABLE Categories ADD Note NVARCHAR(800) NULL
END
GO
Hope it helps. Simone
回答30:
Do something if column is not existing:
BEGIN
IF (COL_LENGTH('[dbo].[Table]', 'Column ') IS NULL)
BEGIN
//Do something
END
END;
Do something if column is existing:
BEGIN
IF (COL_LENGTH('[dbo].[Table]', 'Column ') IS NOT NULL)
BEGIN
//Do something
END
END;
来源：https://stackoverflow.com/questions/133031/how-to-check-if-a-column-exists-in-a-sql-server-table