如果不存在,我需要添加一个特定的列。我有类似以下的内容,但它总是返回false:
IF EXISTS(SELECT *
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'myTableName'
AND COLUMN_NAME = 'myColumnName')
如何检查SQL Server数据库的表中是否存在列?
如果不存在,我需要添加一个特定的列。我有类似以下的内容,但它总是返回false:
IF EXISTS(SELECT *
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'myTableName'
AND COLUMN_NAME = 'myColumnName')
如何检查SQL Server数据库的表中是否存在列?
当前回答
调整以下内容以满足您的具体要求:
if not exists (select
column_name
from
INFORMATION_SCHEMA.columns
where
table_name = 'MyTable'
and column_name = 'MyColumn')
alter table MyTable add MyColumn int
这应该会奏效——仔细检查代码,找出愚蠢的错误;例如,您是否在应用插入的同一数据库上查询INFORMATION_SCHEMA?在这两个语句中,您的表/列名是否有拼写错误?
其他回答
以下查询可用于检查表中是否存在搜索列。我们可以根据搜索结果做出决定,如下所示。
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
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 exist in table
END
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
试试这个。。。
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
调整以下内容以满足您的具体要求:
if not exists (select
column_name
from
INFORMATION_SCHEMA.columns
where
table_name = 'MyTable'
and column_name = 'MyColumn')
alter table MyTable add MyColumn int
这应该会奏效——仔细检查代码,找出愚蠢的错误;例如,您是否在应用插入的同一数据库上查询INFORMATION_SCHEMA?在这两个语句中,您的表/列名是否有拼写错误?