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。
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
我写了以下方法,并尝试将它们参数化,这样你就可以在查询文档中运行它们,或者轻松地使用它们制作一个有用的SP。
一)删除
如果你的表没有数百万条记录,这工作得很好,没有任何Alter命令:
---------------------------------------------------------------
------------------- Just Fill Parameters Value ----------------
---------------------------------------------------------------
DECLARE @DbName AS NVARCHAR(30) = 'MyDb' --< Db Name
DECLARE @Schema AS NVARCHAR(30) = 'dbo' --< Schema
DECLARE @TableName AS NVARCHAR(30) = 'Book' --< Table Name
------------------ /Just Fill Parameters Value ----------------
DECLARE @Query AS NVARCHAR(500) = 'Delete FROM ' + @TableName
EXECUTE sp_executesql @Query
SET @Query=@DbName+'.'+@Schema+'.'+@TableName
DBCC CHECKIDENT (@Query,RESEED, 0)
在我上面的回答中,解决问题中提到的问题的方法是基于@s15199d的回答。
B)截断
如果你的表有数百万条记录,或者你在你的代码中没有任何Alter命令的问题,那么使用这个:
-- Book Student
--
-- | BookId | Field1 | | StudentId | BookId |
-- --------------------- ------------------------
-- | 1 | A | | 2 | 1 |
-- | 2 | B | | 1 | 1 |
-- | 3 | C | | 2 | 3 |
---------------------------------------------------------------
------------------- Just Fill Parameters Value ----------------
---------------------------------------------------------------
DECLARE @DbName AS NVARCHAR(30) = 'MyDb'
DECLARE @Schema AS NVARCHAR(30) = 'dbo'
DECLARE @TableName_ToTruncate AS NVARCHAR(30) = 'Book'
DECLARE @TableName_OfOwnerOfConstraint AS NVARCHAR(30) = 'Student' --< Decelations About FK_Book_Constraint
DECLARE @Ref_ColumnName_In_TableName_ToTruncate AS NVARCHAR(30) = 'BookId' --< Decelations About FK_Book_Constraint
DECLARE @FK_ColumnName_In_TableOfOwnerOfConstraint AS NVARCHAR(30) = 'Fk_BookId' --< Decelations About FK_Book_Constraint
DECLARE @FK_ConstraintName AS NVARCHAR(30) = 'FK_Book_Constraint' --< Decelations About FK_Book_Constraint
------------------ /Just Fill Parameters Value ----------------
DECLARE @Query AS NVARCHAR(2000)
SET @Query= 'ALTER TABLE '+@TableName_OfOwnerOfConstraint+' DROP CONSTRAINT '+@FK_ConstraintName
EXECUTE sp_executesql @Query
SET @Query= 'Truncate Table '+ @TableName_ToTruncate
EXECUTE sp_executesql @Query
SET @Query= 'ALTER TABLE '+@TableName_OfOwnerOfConstraint+' ADD CONSTRAINT '+@FK_ConstraintName+' FOREIGN KEY('+@FK_ColumnName_In_TableOfOwnerOfConstraint+') REFERENCES '+@TableName_ToTruncate+'('+@Ref_ColumnName_In_TableName_ToTruncate+')'
EXECUTE sp_executesql @Query
在上面的回答中,我解决问题中提到的问题的方法是基于@LauroWolffValenteSobrinho的回答。 如果你有不止一个约束,那么你应该把它的代码像我一样附加到上面的查询 此外,您还可以更改上面的代码基@SerjSagan answer来禁用或启用约束
其他回答
下面的工作对我来说,即使有FK约束,并结合以下答案,只删除指定的表:
事务自动回滚 循环使用逗号分隔的列表 执行动态SQL(使用变量中的表名) DELETE和RESEED表(在这个线程中)
USE [YourDB];
DECLARE @TransactionName varchar(20) = 'stopdropandroll';
BEGIN TRAN @TransactionName;
set xact_abort on; /* automatic rollback https://stackoverflow.com/a/1749788/1037948 */
-- ===== DO WORK // =====
-- dynamic sql placeholder
DECLARE @SQL varchar(300);
-- LOOP: https://stackoverflow.com/a/10031803/1037948
-- list of things to loop
DECLARE @delim char = ';';
DECLARE @foreach varchar(MAX) = 'Table;Names;Separated;By;Delimiter' + @delim + 'AnotherName' + @delim + 'Still Another';
DECLARE @token varchar(MAX);
WHILE len(@foreach) > 0
BEGIN
-- set current loop token
SET @token = left(@foreach, charindex(@delim, @foreach+@delim)-1)
-- ======= DO WORK // ===========
-- dynamic sql (parentheses are required): https://stackoverflow.com/a/989111/1037948
SET @SQL = 'DELETE FROM [' + @token + ']; DBCC CHECKIDENT (''' + @token + ''',RESEED, 0);'; -- https://stackoverflow.com/a/11784890
PRINT @SQL;
EXEC (@SQL);
-- ======= // END WORK ===========
-- continue loop, chopping off token
SET @foreach = stuff(@foreach, 1, charindex(@delim, @foreach+@delim), '')
END
-- ===== // END WORK =====
-- review and commit
SELECT @@TRANCOUNT as TransactionsPerformed, @@ROWCOUNT as LastRowsChanged;
COMMIT TRAN @TransactionName;
注意:
我认为这仍然有助于按照你想要删除的顺序声明表(即先删除依赖项)。从这个答案中可以看出,不是循环特定的名称,而是用所有表替换
EXEC sp_MSForEachTable 'DELETE FROM ?; DBCC CHECKIDENT (''?'',RESEED, 0);';
@denver_citizen和@Peter Szanto的回答对我不太适用,但我修改了它们,以解释:
组合键 “删除”和“更新”动作 重新添加时检查索引 dbo以外的模式 同时处理多个表
DECLARE @Debug bit = 0;
-- List of tables to truncate
select
SchemaName, Name
into #tables
from (values
('schema', 'table')
,('schema2', 'table2')
) as X(SchemaName, Name)
BEGIN TRANSACTION TruncateTrans;
with foreignKeys AS (
SELECT
SCHEMA_NAME(fk.schema_id) as SchemaName
,fk.Name as ConstraintName
,OBJECT_NAME(fk.parent_object_id) as TableName
,SCHEMA_NAME(t.SCHEMA_ID) as ReferencedSchemaName
,OBJECT_NAME(fk.referenced_object_id) as ReferencedTableName
,fc.constraint_column_id
,COL_NAME(fk.parent_object_id, fc.parent_column_id) AS ColumnName
,COL_NAME(fk.referenced_object_id, fc.referenced_column_id) as ReferencedColumnName
,fk.delete_referential_action_desc
,fk.update_referential_action_desc
FROM sys.foreign_keys AS fk
JOIN sys.foreign_key_columns AS fc
ON fk.object_id = fc.constraint_object_id
JOIN #tables tbl
ON OBJECT_NAME(fc.referenced_object_id) = tbl.Name
JOIN sys.tables t on OBJECT_NAME(t.object_id) = tbl.Name
and SCHEMA_NAME(t.schema_id) = tbl.SchemaName
and t.OBJECT_ID = fc.referenced_object_id
)
select
quotename(fk.ConstraintName) AS ConstraintName
,quotename(fk.SchemaName) + '.' + quotename(fk.TableName) AS TableName
,quotename(fk.ReferencedSchemaName) + '.' + quotename(fk.ReferencedTableName) AS ReferencedTableName
,replace(fk.delete_referential_action_desc, '_', ' ') AS DeleteAction
,replace(fk.update_referential_action_desc, '_', ' ') AS UpdateAction
,STUFF((
SELECT ',' + quotename(fk2.ColumnName)
FROM foreignKeys fk2
WHERE fk2.ConstraintName = fk.ConstraintName and fk2.SchemaName = fk.SchemaName
ORDER BY fk2.constraint_column_id
FOR XML PATH('')
),1,1,'') AS ColumnNames
,STUFF((
SELECT ',' + quotename(fk2.ReferencedColumnName)
FROM foreignKeys fk2
WHERE fk2.ConstraintName = fk.ConstraintName and fk2.SchemaName = fk.SchemaName
ORDER BY fk2.constraint_column_id
FOR XML PATH('')
),1,1,'') AS ReferencedColumnNames
into #FKs
from foreignKeys fk
GROUP BY fk.SchemaName, fk.ConstraintName, fk.TableName, fk.ReferencedSchemaName, fk.ReferencedTableName, fk.delete_referential_action_desc, fk.update_referential_action_desc
-- Drop FKs
select
identity(int,1,1) as ID,
'ALTER TABLE ' + fk.TableName + ' DROP CONSTRAINT ' + fk.ConstraintName AS script
into #scripts
from #FKs fk
-- Truncate
insert into #scripts
select distinct
'TRUNCATE TABLE ' + quotename(tbl.SchemaName) + '.' + quotename(tbl.Name) AS script
from #tables tbl
-- Recreate
insert into #scripts
select
'ALTER TABLE ' + fk.TableName +
' WITH CHECK ADD CONSTRAINT ' + fk.ConstraintName +
' FOREIGN KEY ('+ fk.ColumnNames +')' +
' REFERENCES ' + fk.ReferencedTableName +' ('+ fk.ReferencedColumnNames +')' +
' ON DELETE ' + fk.DeleteAction COLLATE Latin1_General_CI_AS_KS_WS + ' ON UPDATE ' + fk.UpdateAction COLLATE Latin1_General_CI_AS_KS_WS AS script
from #FKs fk
DECLARE @script nvarchar(MAX);
DECLARE curScripts CURSOR FOR
select script
from #scripts
order by ID
OPEN curScripts
WHILE 1=1 BEGIN
FETCH NEXT FROM curScripts INTO @script
IF @@FETCH_STATUS != 0 BREAK;
print @script;
IF @Debug = 0
EXEC (@script);
END
CLOSE curScripts
DEALLOCATE curScripts
drop table #scripts
drop table #FKs
drop table #tables
COMMIT TRANSACTION TruncateTrans;
你可以按照这个步骤来做, 通过重新播种表,可以删除表中的数据。
delete from table_name
dbcc checkident('table_name',reseed,0)
如果出现错误,则必须重新播种主表。
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。
如果不删除约束,就不能截断表。disable也不行。你需要放下一切。我已经做了一个脚本,删除所有约束,然后重新创建。
请确保将其包装在事务中;)
SET NOCOUNT ON
GO
DECLARE @table TABLE(
RowId INT PRIMARY KEY IDENTITY(1, 1),
ForeignKeyConstraintName NVARCHAR(200),
ForeignKeyConstraintTableSchema NVARCHAR(200),
ForeignKeyConstraintTableName NVARCHAR(200),
ForeignKeyConstraintColumnName NVARCHAR(200),
PrimaryKeyConstraintName NVARCHAR(200),
PrimaryKeyConstraintTableSchema NVARCHAR(200),
PrimaryKeyConstraintTableName NVARCHAR(200),
PrimaryKeyConstraintColumnName NVARCHAR(200)
)
INSERT INTO @table(ForeignKeyConstraintName, ForeignKeyConstraintTableSchema, ForeignKeyConstraintTableName, ForeignKeyConstraintColumnName)
SELECT
U.CONSTRAINT_NAME,
U.TABLE_SCHEMA,
U.TABLE_NAME,
U.COLUMN_NAME
FROM
INFORMATION_SCHEMA.KEY_COLUMN_USAGE U
INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS C
ON U.CONSTRAINT_NAME = C.CONSTRAINT_NAME
WHERE
C.CONSTRAINT_TYPE = 'FOREIGN KEY'
UPDATE @table SET
PrimaryKeyConstraintName = UNIQUE_CONSTRAINT_NAME
FROM
@table T
INNER JOIN INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS R
ON T.ForeignKeyConstraintName = R.CONSTRAINT_NAME
UPDATE @table SET
PrimaryKeyConstraintTableSchema = TABLE_SCHEMA,
PrimaryKeyConstraintTableName = TABLE_NAME
FROM @table T
INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS C
ON T.PrimaryKeyConstraintName = C.CONSTRAINT_NAME
UPDATE @table SET
PrimaryKeyConstraintColumnName = COLUMN_NAME
FROM @table T
INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE U
ON T.PrimaryKeyConstraintName = U.CONSTRAINT_NAME
--DROP CONSTRAINT:
DECLARE @dynSQL varchar(MAX);
DECLARE cur CURSOR FOR
SELECT
'
ALTER TABLE [' + ForeignKeyConstraintTableSchema + '].[' + ForeignKeyConstraintTableName + ']
DROP CONSTRAINT ' + ForeignKeyConstraintName + '
'
FROM
@table
OPEN cur
FETCH cur into @dynSQL
WHILE @@FETCH_STATUS = 0
BEGIN
exec(@dynSQL)
print @dynSQL
FETCH cur into @dynSQL
END
CLOSE cur
DEALLOCATE cur
---------------------
--HERE GOES YOUR TRUNCATES!!!!!
--HERE GOES YOUR TRUNCATES!!!!!
--HERE GOES YOUR TRUNCATES!!!!!
truncate table your_table
--HERE GOES YOUR TRUNCATES!!!!!
--HERE GOES YOUR TRUNCATES!!!!!
--HERE GOES YOUR TRUNCATES!!!!!
---------------------
--ADD CONSTRAINT:
DECLARE cur2 CURSOR FOR
SELECT
'
ALTER TABLE [' + ForeignKeyConstraintTableSchema + '].[' + ForeignKeyConstraintTableName + ']
ADD CONSTRAINT ' + ForeignKeyConstraintName + ' FOREIGN KEY(' + ForeignKeyConstraintColumnName + ') REFERENCES [' + PrimaryKeyConstraintTableSchema + '].[' + PrimaryKeyConstraintTableName + '](' + PrimaryKeyConstraintColumnName + ')
'
FROM
@table
OPEN cur2
FETCH cur2 into @dynSQL
WHILE @@FETCH_STATUS = 0
BEGIN
exec(@dynSQL)
print @dynSQL
FETCH cur2 into @dynSQL
END
CLOSE cur2
DEALLOCATE cur2