SQL验证列的约束

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当规则类型为唯一时：SELECT 字段名 FROM 表名 GROUP BY 字段名 HAVING COUNT(1) >0

当规则类型为非空时：SELECT * FROM 表名 WHERE 字段名 IS NULL

当规则类型为主键时：SELECT COUNT(1) FROM USER_CONSTRAINTS UC,USER_CONS_COLUMNS UCC WHERE UC.CONSTRAINT_NAME = UCC.CONSTRAINT_NAME AND UC.CONSTRAINT_TYPE = 'P' AND UCC.TABLE_NAME = 表名 AND UCC.COLUMN_NAME = 字段名

当规则类型为外键时：SELECT * FROM 表名 WHERE 关联字段 NOT IN (SELECT DISTINCT关联字段 FROM  关联表)