--查询特定表的主键信息
方式一：
SELECT COLUMN_NAME
FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE OBJECTPROPERTY(OBJECT_ID(CONSTRAINT_SCHEMA + '.' + QUOTENAME(CONSTRAINT_NAME)), 'IsPrimaryKey') = 1
AND TABLE_NAME = 'TableName' AND TABLE_SCHEMA = 'Schema'
方式二：
SELECT KU.table_name as TABLENAME,column_name as PRIMARYKEYCOLUMN
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS AS TC
INNER JOIN
INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS KU
ON TC.CONSTRAINT_TYPE = 'PRIMARY KEY' AND
TC.CONSTRAINT_NAME = KU.CONSTRAINT_NAME AND
KU.table_name='yourTableName'
ORDER BY KU.TABLE_NAME, KU.ORDINAL_POSITION;
方式三：
SELECT * FROM sys.objects
WHERE type = 'PK'
AND object_id = OBJECT_ID ('tableName')
方式四：
SELECT * FROM sys.objects
WHERE type = 'PK'
AND parent_object_id = OBJECT_ID ('tableName')
--查询所有表的主键信息
方式一：
SELECT A.NAME AS 表名,B.NAME AS 主键名
FROM SYSOBJECTS A
JOIN SYSOBJECTS B
ON A.ID=B.PARENT_OBJ
AND A.XTYPE='U' AND B.XTYPE='PK'
方式二：
SELECT a.name AS '表名',
e.name AS '主键字段'
FROM sysobjects AS a --对象表，结合a.xtype='U'条件，查用户表
LEFT JOIN sysobjects AS b --对象表，结合b.xtype='PK'条件，查主键约束
ON a.id=b.parent_obj
LEFT JOIN sysindexes AS c --索引表，根据（主键）约束名称匹配，查对应字段索引
ON a.id=c.id AND b.name=c.name
LEFT JOIN sysindexkeys AS d --索引中对应键、列的表，根据索引匹配，查字段id
ON a.id=d.id AND c.indid=d.indid
LEFT JOIN syscolumns AS e --字段表，根据字段id匹配，查字段名称
ON a.id=e.id AND d.colid=e.colid
WHERE a.xtype='U'
AND b.xtype='PK'
