sql查詢約束

① sql server怎麼查詢某一表的某一欄位是否有約束

示例:
CREATE TABLE AA (
BB INT UNIQUE
);
SELECT

tab.name AS [表名],
idx.name AS [約束名稱],
col.name AS [約束列名]
FROM
sys.indexes idx
JOIN sys.index_columns idxCol
ON (idx.object_id = idxCol.object_id
AND idx.index_id = idxCol.index_id
AND idx.is_unique_constraint = 1)
JOIN sys.tables tab
ON (idx.object_id = tab.object_id)
JOIN sys.columns col
ON (idx.object_id = col.object_id
AND idxCol.column_id = col.column_id)
WHERE
tab.name = 'AA'
結果:
表名 約束名稱 約束列名
AA UQ__AA__3214B5C34460231C BB

② SQL中用語句查看錶列的約束以及解除約束

SELECT
USER_CONS_COLUMNS.CONSTRAINT_NAMEAS約束名,
USER_CONS_COLUMNS.TABLE_NAMEAS表名,
USER_CONS_COLUMNS.COLUMN_NAMEAS列名,
USER_CONS_COLUMNS.POSITIONAS位置,
CONSTRAINT_TYPE,
SEARCH_CONDITION
FROM
USER_CONSTRAINTS
JOINUSER_CONS_COLUMNS
ON(USER_CONSTRAINTS.CONSTRAINT_NAME
=USER_CONS_COLUMNS.CONSTRAINT_NAME)
WHERE
CONSTRAINT_TYPEIN('C','V','O');

其實主要就是看

USER_CONSTRAINTS與 USER_CONS_COLUMNS 這2個視圖.

資料庫管理員的話

可以看

DBA_CONSTRAINTS與 DBA_CONS_COLUMNS 這2個視圖.

③ SQL資料庫中如何查看約束有那些方法求指教。

可以從下面的數據字典中查詢想要的約束信息

dba_constraints
dba_cons_columns

④ sql server 查詢約束鍵在哪個表的腳本

查詢一個表的所有外鍵
SELECT主鍵列ID=b.rkey
,主鍵列名=(=b.rkeyANDid=b.rkeyid)
,外鍵表ID=b.fkeyid
,外鍵表名稱=object_name(b.fkeyid)
,外鍵列ID=b.fkey
,外鍵列名=(=b.fkeyANDid=b.fkeyid)
,級聯更新=ObjectProperty(a.id,'CnstIsUpdateCascade')
,級聯刪除=ObjectProperty(a.id,'CnstIsDeleteCascade')
FROMsysobjectsa
joinsysforeignkeysbona.id=b.constid
joinsysobjectscona.parent_obj=c.id
wherea.xtype='f'ANDc.xtype='U'
andobject_name(b.rkeyid)='titles'

SELECT*
FROMinformation_schema.columns
WHERETABLE_CATALOG='資料庫名'
ANDTABLE_NAME='表名'
ANDCOLUMN_NAME='列名'

select*
fromsyscolumns
whereid=object_id('tableName')andname='fieldName'

⑤ sql語句，怎麼查看一個表中的所有約束

sp_mshelpcolumns student
如上可以看到該表的所有結構、約束、默認值等

⑥ sql查詢表中的約束

exec sp_helpconstraint S

ALTER TABLE S DROP CONSTRAINT 你自己的約束名稱;

⑦ sql 約束名

SQL 約束（Constraints）

• SQL 約束用於規定表中的數據規則。

• 如果存在違反約束的數據行為，行為會被約束終止。

• 約束可以在創建表時規定（通過 CREATE TABLE 語句），或者在表創建之後規定（通過 ALTER TABLE 語句）。

⑧ sqlserver資料庫里怎麼查找一個表裡的約束，要查出 約束名、列名、約束類型用sql語句查詢

主鍵約束
SELECT
tab.name AS [表名],
idx.name AS [主鍵名稱],
col.name AS [主鍵列名]
FROM
sys.indexes idx
JOIN sys.index_columns idxCol
ON (idx.object_id = idxCol.object_id
AND idx.index_id = idxCol.index_id
AND idx.is_primary_key = 1)
JOIN sys.tables tab
ON (idx.object_id = tab.object_id)
JOIN sys.columns col
ON (idx.object_id = col.object_id
AND idxCol.column_id = col.column_id);

唯一約束
SELECT
tab.name AS [表名],
idx.name AS [約束名稱],
col.name AS [約束列名]
FROM
sys.indexes idx
JOIN sys.index_columns idxCol
ON (idx.object_id = idxCol.object_id
AND idx.index_id = idxCol.index_id
AND idx.is_unique_constraint = 1)
JOIN sys.tables tab
ON (idx.object_id = tab.object_id)
JOIN sys.columns col
ON (idx.object_id = col.object_id
AND idxCol.column_id = col.column_id);

外鍵約束
select
oSub.name AS [子表名稱],
fk.name AS [外鍵名稱],
SubCol.name AS [子表列名],
oMain.name AS [主表名稱],
MainCol.name AS [主表列名]
from
sys.foreign_keys fk
JOIN sys.all_objects oSub
ON (fk.parent_object_id = oSub.object_id)
JOIN sys.all_objects oMain
ON (fk.referenced_object_id = oMain.object_id)
JOIN sys.foreign_key_columns fkCols
ON (fk.object_id = fkCols.constraint_object_id)
JOIN sys.columns SubCol
ON (oSub.object_id = SubCol.object_id
AND fkCols.parent_column_id = SubCol.column_id)
JOIN sys.columns MainCol
ON (oMain.object_id = MainCol.object_id
AND fkCols.referenced_column_id = MainCol.column_id)

Check約束
SELECT
tab.name AS [表名],
chk.name AS [Check約束名],
col.name AS [列名],
chk.definition
FROM
sys.check_constraints chk
JOIN sys.tables tab
ON (chk.parent_object_id = tab.object_id)
JOIN sys.columns col
ON (chk.parent_object_id = col.object_id
AND chk.parent_column_id = col.column_id)

⑨ 如何寫SQL查詢一個約束條件的內容

在oracle中有兩個系統表可以查詢
user_constraints約束表，記錄該用戶的所有約束。如非空，索引等等。
user_cons_columns約束欄位表，記錄每個約束涉及到的所有欄位。