使用MSSQL2005，如果我首先截断子表(具有FK关系的主键的表)，我可以截断带有外键约束的表吗?
我知道我也可以
使用不带where子句的DELETE，然后RESEED标识(或) 删除FK，截断表，并重新创建FK。
我认为只要我在父表之前截断子表，我就可以不做上面的任何一个选项，但我得到了这个错误:
不能截断表'TableName'，因为它被一个FOREIGN KEY约束引用。
当前回答
我刚刚发现，只要先禁用子表上的外键约束，就可以在父表上使用TRUNCATE表。 如。
子表上的外键约束child_par_ref引用PARENT_TABLE
ALTER TABLE CHILD_TABLE DISABLE CONSTRAINT child_par_ref;
TRUNCATE TABLE CHILD_TABLE;
TRUNCATE TABLE PARENT_TABLE;
ALTER TABLE CHILD_TABLE ENABLE CONSTRAINT child_par_ref;
其他回答
下面是我写的一个脚本，以使这个过程自动化。我希望这能有所帮助。
SET NOCOUNT ON
-- GLOBAL VARIABLES
DECLARE @i int
DECLARE @Debug bit
DECLARE @Recycle bit
DECLARE @Verbose bit
DECLARE @TableName varchar(80)
DECLARE @ColumnName varchar(80)
DECLARE @ReferencedTableName varchar(80)
DECLARE @ReferencedColumnName varchar(80)
DECLARE @ConstraintName varchar(250)
DECLARE @CreateStatement varchar(max)
DECLARE @DropStatement varchar(max)
DECLARE @TruncateStatement varchar(max)
DECLARE @CreateStatementTemp varchar(max)
DECLARE @DropStatementTemp varchar(max)
DECLARE @TruncateStatementTemp varchar(max)
DECLARE @Statement varchar(max)
-- 1 = Will not execute statements
SET @Debug = 0
-- 0 = Will not create or truncate storage table
-- 1 = Will create or truncate storage table
SET @Recycle = 0
-- 1 = Will print a message on every step
set @Verbose = 1
SET @i = 1
SET @CreateStatement = 'ALTER TABLE [dbo].[<tablename>] WITH NOCHECK ADD CONSTRAINT [<constraintname>] FOREIGN KEY([<column>]) REFERENCES [dbo].[<reftable>] ([<refcolumn>])'
SET @DropStatement = 'ALTER TABLE [dbo].[<tablename>] DROP CONSTRAINT [<constraintname>]'
SET @TruncateStatement = 'TRUNCATE TABLE [<tablename>]'
-- Drop Temporary tables
DROP TABLE #FKs
-- GET FKs
SELECT ROW_NUMBER() OVER (ORDER BY OBJECT_NAME(parent_object_id), clm1.name) as ID,
OBJECT_NAME(constraint_object_id) as ConstraintName,
OBJECT_NAME(parent_object_id) as TableName,
clm1.name as ColumnName,
OBJECT_NAME(referenced_object_id) as ReferencedTableName,
clm2.name as ReferencedColumnName
INTO #FKs
FROM sys.foreign_key_columns fk
JOIN sys.columns clm1
ON fk.parent_column_id = clm1.column_id
AND fk.parent_object_id = clm1.object_id
JOIN sys.columns clm2
ON fk.referenced_column_id = clm2.column_id
AND fk.referenced_object_id= clm2.object_id
WHERE OBJECT_NAME(parent_object_id) not in ('//tables that you do not wont to be truncated')
ORDER BY OBJECT_NAME(parent_object_id)
-- Prepare Storage Table
IF Not EXISTS(SELECT 1 FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = 'Internal_FK_Definition_Storage')
BEGIN
IF @Verbose = 1
PRINT '1. Creating Process Specific Tables...'
-- CREATE STORAGE TABLE IF IT DOES NOT EXISTS
CREATE TABLE [Internal_FK_Definition_Storage]
(
ID int not null identity(1,1) primary key,
FK_Name varchar(250) not null,
FK_CreationStatement varchar(max) not null,
FK_DestructionStatement varchar(max) not null,
Table_TruncationStatement varchar(max) not null
)
END
ELSE
BEGIN
IF @Recycle = 0
BEGIN
IF @Verbose = 1
PRINT '1. Truncating Process Specific Tables...'
-- TRUNCATE TABLE IF IT ALREADY EXISTS
TRUNCATE TABLE [Internal_FK_Definition_Storage]
END
ELSE
PRINT '1. Process specific table will be recycled from previous execution...'
END
IF @Recycle = 0
BEGIN
IF @Verbose = 1
PRINT '2. Backing up Foreign Key Definitions...'
-- Fetch and persist FKs
WHILE (@i <= (SELECT MAX(ID) FROM #FKs))
BEGIN
SET @ConstraintName = (SELECT ConstraintName FROM #FKs WHERE ID = @i)
SET @TableName = (SELECT TableName FROM #FKs WHERE ID = @i)
SET @ColumnName = (SELECT ColumnName FROM #FKs WHERE ID = @i)
SET @ReferencedTableName = (SELECT ReferencedTableName FROM #FKs WHERE ID = @i)
SET @ReferencedColumnName = (SELECT ReferencedColumnName FROM #FKs WHERE ID = @i)
SET @DropStatementTemp = REPLACE(REPLACE(@DropStatement,'<tablename>',@TableName),'<constraintname>',@ConstraintName)
SET @CreateStatementTemp = REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(@CreateStatement,'<tablename>',@TableName),'<column>',@ColumnName),'<constraintname>',@ConstraintName),'<reftable>',@ReferencedTableName),'<refcolumn>',@ReferencedColumnName)
SET @TruncateStatementTemp = REPLACE(@TruncateStatement,'<tablename>',@TableName)
INSERT INTO [Internal_FK_Definition_Storage]
SELECT @ConstraintName, @CreateStatementTemp, @DropStatementTemp, @TruncateStatementTemp
SET @i = @i + 1
IF @Verbose = 1
PRINT ' > Backing up [' + @ConstraintName + '] from [' + @TableName + ']'
END
END
ELSE
PRINT '2. Backup up was recycled from previous execution...'
IF @Verbose = 1
PRINT '3. Dropping Foreign Keys...'
-- DROP FOREING KEYS
SET @i = 1
WHILE (@i <= (SELECT MAX(ID) FROM [Internal_FK_Definition_Storage]))
BEGIN
SET @ConstraintName = (SELECT FK_Name FROM [Internal_FK_Definition_Storage] WHERE ID = @i)
SET @Statement = (SELECT FK_DestructionStatement FROM [Internal_FK_Definition_Storage] WITH (NOLOCK) WHERE ID = @i)
IF @Debug = 1
PRINT @Statement
ELSE
EXEC(@Statement)
SET @i = @i + 1
IF @Verbose = 1
PRINT ' > Dropping [' + @ConstraintName + ']'
END
IF @Verbose = 1
PRINT '4. Truncating Tables...'
-- TRUNCATE TABLES
SET @i = 1
WHILE (@i <= (SELECT MAX(ID) FROM [Internal_FK_Definition_Storage]))
BEGIN
SET @Statement = (SELECT Table_TruncationStatement FROM [Internal_FK_Definition_Storage] WHERE ID = @i)
IF @Debug = 1
PRINT @Statement
ELSE
EXEC(@Statement)
SET @i = @i + 1
IF @Verbose = 1
PRINT ' > ' + @Statement
END
IF @Verbose = 1
PRINT '5. Re-creating Foreign Keys...'
-- CREATE FOREING KEYS
SET @i = 1
WHILE (@i <= (SELECT MAX(ID) FROM [Internal_FK_Definition_Storage]))
BEGIN
SET @ConstraintName = (SELECT FK_Name FROM [Internal_FK_Definition_Storage] WHERE ID = @i)
SET @Statement = (SELECT FK_CreationStatement FROM [Internal_FK_Definition_Storage] WHERE ID = @i)
IF @Debug = 1
PRINT @Statement
ELSE
EXEC(@Statement)
SET @i = @i + 1
IF @Verbose = 1
PRINT ' > Re-creating [' + @ConstraintName + ']'
END
IF @Verbose = 1
PRINT '6. Process Completed'
好吧，因为我没有找到我使用的非常简单的解决方案的例子，这是:
删除外键; 截断表 重新创建外键
是这样的:
1)查找导致失败的外键名称(例如:FK_PROBLEM_REASON，带字段ID，来自表TABLE_OWNING_CONSTRAINT) 2)从表中删除该键:
ALTER TABLE TABLE_OWNING_CONSTRAINT DROP CONSTRAINT FK_PROBLEM_REASON
3)截断招聘表
TRUNCATE TABLE TABLE_TO_TRUNCATE
4)重新添加第一个表的键:
ALTER TABLE TABLE_OWNING_CONSTRAINT ADD CONSTRAINT FK_PROBLEM_REASON FOREIGN KEY(ID) REFERENCES TABLE_TO_TRUNCATE (ID)
就是这样。
如果您以任何频率执行此操作，甚至在时间表上，我绝对不会明确地使用DML语句。写入事务日志的成本非常高，将整个数据库设置为SIMPLE恢复模式以截断一个表是荒谬的。
最好的办法，不幸是艰苦或费力的办法。这是:
减少约束 截断表 重新创建约束
我这样做的过程包括以下步骤:
在SSMS中，右键单击有问题的表，并选择查看依赖项 记下引用的表格(如果有的话) 回到对象资源管理器，展开Keys节点并记下外键(如果有的话) 开始编写脚本(删除/截断/重新创建)
这种性质的脚本应该在begin tran和commit tran块中完成。
上面@denver_citizen提供的解决方案并不适合我，但我喜欢它的精神，所以我修改了一些东西:
使其成为存储过程 更改了外键填充和重新创建的方式 原始脚本截断所有引用的表，当引用的表有其他外键引用时，这可能导致违反外键错误。这个脚本只截断作为参数指定的表。由用户决定是否在所有表上以正确的顺序多次调用此存储过程
为了公众的利益，以下是更新后的脚本:
CREATE PROCEDURE [dbo].[truncate_non_empty_table]
@TableToTruncate VARCHAR(64)
AS
BEGIN
SET NOCOUNT ON
-- GLOBAL VARIABLES
DECLARE @i int
DECLARE @Debug bit
DECLARE @Recycle bit
DECLARE @Verbose bit
DECLARE @TableName varchar(80)
DECLARE @ColumnName varchar(80)
DECLARE @ReferencedTableName varchar(80)
DECLARE @ReferencedColumnName varchar(80)
DECLARE @ConstraintName varchar(250)
DECLARE @CreateStatement varchar(max)
DECLARE @DropStatement varchar(max)
DECLARE @TruncateStatement varchar(max)
DECLARE @CreateStatementTemp varchar(max)
DECLARE @DropStatementTemp varchar(max)
DECLARE @TruncateStatementTemp varchar(max)
DECLARE @Statement varchar(max)
-- 1 = Will not execute statements
SET @Debug = 0
-- 0 = Will not create or truncate storage table
-- 1 = Will create or truncate storage table
SET @Recycle = 0
-- 1 = Will print a message on every step
set @Verbose = 1
SET @i = 1
SET @CreateStatement = 'ALTER TABLE [dbo].[<tablename>] WITH NOCHECK ADD CONSTRAINT [<constraintname>] FOREIGN KEY([<column>]) REFERENCES [dbo].[<reftable>] ([<refcolumn>])'
SET @DropStatement = 'ALTER TABLE [dbo].[<tablename>] DROP CONSTRAINT [<constraintname>]'
SET @TruncateStatement = 'TRUNCATE TABLE [<tablename>]'
-- Drop Temporary tables
IF OBJECT_ID('tempdb..#FKs') IS NOT NULL
DROP TABLE #FKs
-- GET FKs
SELECT ROW_NUMBER() OVER (ORDER BY OBJECT_NAME(parent_object_id), clm1.name) as ID,
OBJECT_NAME(constraint_object_id) as ConstraintName,
OBJECT_NAME(parent_object_id) as TableName,
clm1.name as ColumnName,
OBJECT_NAME(referenced_object_id) as ReferencedTableName,
clm2.name as ReferencedColumnName
INTO #FKs
FROM sys.foreign_key_columns fk
JOIN sys.columns clm1
ON fk.parent_column_id = clm1.column_id
AND fk.parent_object_id = clm1.object_id
JOIN sys.columns clm2
ON fk.referenced_column_id = clm2.column_id
AND fk.referenced_object_id= clm2.object_id
--WHERE OBJECT_NAME(parent_object_id) not in ('//tables that you do not wont to be truncated')
WHERE OBJECT_NAME(referenced_object_id) = @TableToTruncate
ORDER BY OBJECT_NAME(parent_object_id)
-- Prepare Storage Table
IF Not EXISTS(SELECT 1 FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = 'Internal_FK_Definition_Storage')
BEGIN
IF @Verbose = 1
PRINT '1. Creating Process Specific Tables...'
-- CREATE STORAGE TABLE IF IT DOES NOT EXISTS
CREATE TABLE [Internal_FK_Definition_Storage]
(
ID int not null identity(1,1) primary key,
FK_Name varchar(250) not null,
FK_CreationStatement varchar(max) not null,
FK_DestructionStatement varchar(max) not null,
Table_TruncationStatement varchar(max) not null
)
END
ELSE
BEGIN
IF @Recycle = 0
BEGIN
IF @Verbose = 1
PRINT '1. Truncating Process Specific Tables...'
-- TRUNCATE TABLE IF IT ALREADY EXISTS
TRUNCATE TABLE [Internal_FK_Definition_Storage]
END
ELSE
PRINT '1. Process specific table will be recycled from previous execution...'
END
IF @Recycle = 0
BEGIN
IF @Verbose = 1
PRINT '2. Backing up Foreign Key Definitions...'
-- Fetch and persist FKs
WHILE (@i <= (SELECT MAX(ID) FROM #FKs))
BEGIN
SET @ConstraintName = (SELECT ConstraintName FROM #FKs WHERE ID = @i)
SET @TableName = (SELECT TableName FROM #FKs WHERE ID = @i)
SET @ColumnName = (SELECT ColumnName FROM #FKs WHERE ID = @i)
SET @ReferencedTableName = (SELECT ReferencedTableName FROM #FKs WHERE ID = @i)
SET @ReferencedColumnName = (SELECT ReferencedColumnName FROM #FKs WHERE ID = @i)
SET @DropStatementTemp = REPLACE(REPLACE(@DropStatement,'<tablename>',@TableName),'<constraintname>',@ConstraintName)
SET @CreateStatementTemp = REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(@CreateStatement,'<tablename>',@TableName),'<column>',@ColumnName),'<constraintname>',@ConstraintName),'<reftable>',@ReferencedTableName),'<refcolumn>',@ReferencedColumnName)
SET @TruncateStatementTemp = REPLACE(@TruncateStatement,'<tablename>',@TableName)
INSERT INTO [Internal_FK_Definition_Storage]
SELECT @ConstraintName, @CreateStatementTemp, @DropStatementTemp, @TruncateStatementTemp
SET @i = @i + 1
IF @Verbose = 1
PRINT ' > Backing up [' + @ConstraintName + '] from [' + @TableName + ']'
END
END
ELSE
PRINT '2. Backup up was recycled from previous execution...'
IF @Verbose = 1
PRINT '3. Dropping Foreign Keys...'
-- DROP FOREING KEYS
SET @i = 1
WHILE (@i <= (SELECT MAX(ID) FROM [Internal_FK_Definition_Storage]))
BEGIN
SET @ConstraintName = (SELECT FK_Name FROM [Internal_FK_Definition_Storage] WHERE ID = @i)
SET @Statement = (SELECT FK_DestructionStatement FROM [Internal_FK_Definition_Storage] WITH (NOLOCK) WHERE ID = @i)
IF @Debug = 1
PRINT @Statement
ELSE
EXEC(@Statement)
SET @i = @i + 1
IF @Verbose = 1
PRINT ' > Dropping [' + @ConstraintName + ']'
END
IF @Verbose = 1
PRINT '4. Truncating Tables...'
-- TRUNCATE TABLES
-- SzP: commented out as the tables to be truncated might also contain tables that has foreign keys
-- to resolve this the stored procedure should be called recursively, but I dont have the time to do it...
/*
SET @i = 1
WHILE (@i <= (SELECT MAX(ID) FROM [Internal_FK_Definition_Storage]))
BEGIN
SET @Statement = (SELECT Table_TruncationStatement FROM [Internal_FK_Definition_Storage] WHERE ID = @i)
IF @Debug = 1
PRINT @Statement
ELSE
EXEC(@Statement)
SET @i = @i + 1
IF @Verbose = 1
PRINT ' > ' + @Statement
END
*/
IF @Verbose = 1
PRINT ' > TRUNCATE TABLE [' + @TableToTruncate + ']'
IF @Debug = 1
PRINT 'TRUNCATE TABLE [' + @TableToTruncate + ']'
ELSE
EXEC('TRUNCATE TABLE [' + @TableToTruncate + ']')
IF @Verbose = 1
PRINT '5. Re-creating Foreign Keys...'
-- CREATE FOREING KEYS
SET @i = 1
WHILE (@i <= (SELECT MAX(ID) FROM [Internal_FK_Definition_Storage]))
BEGIN
SET @ConstraintName = (SELECT FK_Name FROM [Internal_FK_Definition_Storage] WHERE ID = @i)
SET @Statement = (SELECT FK_CreationStatement FROM [Internal_FK_Definition_Storage] WHERE ID = @i)
IF @Debug = 1
PRINT @Statement
ELSE
EXEC(@Statement)
SET @i = @i + 1
IF @Verbose = 1
PRINT ' > Re-creating [' + @ConstraintName + ']'
END
IF @Verbose = 1
PRINT '6. Process Completed'
END
SET FOREIGN_KEY_CHECKS=0;
TRUNCATE table1;
TRUNCATE table2;
SET FOREIGN_KEY_CHECKS=1;
引用-截断外键约束表
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