sql-server – 信息架构和主键

如何使用主键打印出列的“主键”？

如果表具有主键,而不是带有主键的一列和其他列在keyType中为空,则为所有列获取“主键”.

SELECT c.TABLE_NAME,c.COLUMN_NAME,c.DATA_TYPE,c.Column_default,c.character_maximum_length,c.numeric_precision,c.is_nullable,CASE 
            WHEN u.CONSTRAINT_TYPE = 'PRIMARY KEY' THEN 'primary key'
            ELSE '' 
          END AS KeyType
     FROM informatION_SCHEMA.COLUMNS as c
LEFT JOIN information_schema.table_constraints as u ON c.table_name = u.table_name
 ORDER BY table_name

解决方法

SELECT  c.TABLE_NAME,CASE WHEN pk.COLUMN_NAME IS NOT NULL THEN 'PRIMARY KEY' ELSE '' END AS KeyType
FROM informatION_SCHEMA.COLUMNS c
LEFT JOIN (
            SELECT ku.TABLE_CATALOG,ku.TABLE_SCHEMA,ku.TABLE_NAME,ku.COLUMN_NAME
            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
         )   pk 
ON  c.TABLE_CATALOG = pk.TABLE_CATALOG
            AND c.TABLE_SCHEMA = pk.TABLE_SCHEMA
            AND c.TABLE_NAME = pk.TABLE_NAME
            AND c.COLUMN_NAME = pk.COLUMN_NAME
ORDER BY c.TABLE_SCHEMA,c.TABLE_NAME,c.ORDINAL_POSITION