Question

我有一个MySql select查询用于选择所有列名：

SELECT info.COLUMN_NAME AS `NAME`, info.TABLE_SCHEMA AS `TABLESCHEMA`,
    info.TABLE_NAME AS `TABLENAME`, info.ORDINAL_POSITION AS `POSITION`,
    info.IS_NULLABLE AS `ISNULLABLE`, info.DATA_TYPE AS `DATATYPE`,
    tc.CONSTRAINT_TYPE AS `CONSTRAINTTYPE`, 
    kcufk.TABLE_SCHEMA AS `REFRENCESCHEMA`,
    kcufk.TABLE_NAME AS `REFRENCETABLE`,
    kcufk.COLUMN_NAME AS `REFRENCECOLUMN` FROM 
    INFORMATION_SCHEMA.`COLUMNS` info LEFT OUTER JOIN INFORMATION_SCHEMA.`KEY_COLUMN_USAGE` kcu
    ON kcu.COLUMN_NAME = info.COLUMN_NAME AND kcu.TABLE_NAME = info.TABLE_NAME LEFT OUTER JOIN 
    INFORMATION_SCHEMA.`TABLE_CONSTRAINTS` tc ON tc.CONSTRAINT_NAME = kcu.CONSTRAINT_NAME
    AND tc.TABLE_NAME = kcu.TABLE_NAME LEFT OUTER JOIN INFORMATION_SCHEMA.`REFERENTIAL_CONSTRAINTS`
    rk ON rk.CONSTRAINT_NAME = tc.CONSTRAINT_NAME LEFT OUTER JOIN INFORMATION_SCHEMA.`KEY_COLUMN_USAGE` 
    kcufk ON kcufk.CONSTRAINT_NAME = rk.UNIQUE_CONSTRAINT_NAME WHERE info.TABLE_NAME = 'reportsetting' AND 
    info.TABLE_SCHEMA = 'core' ORDER BY info.ORDINAL_POSITION ASC

问题是在执行此查询时，外键会多次出现。

What am I doing wrong in this query?

Answer 1

使用联接和条件更新了您的查询，这应该为您提供所需的内容

    SELECT info.COLUMN_NAME AS `NAME`, info.TABLE_SCHEMA AS `TABLESCHEMA`,
    info.TABLE_NAME AS `TABLENAME`, info.ORDINAL_POSITION AS `POSITION`,
    info.IS_NULLABLE AS `ISNULLABLE`, info.DATA_TYPE AS `DATATYPE`,
    tc.CONSTRAINT_TYPE AS `CONSTRAINTTYPE`, 
    kcufk.TABLE_SCHEMA AS `REFRENCESCHEMA`,
    kcufk.TABLE_NAME AS `REFRENCETABLE`,
    kcufk.COLUMN_NAME AS `REFRENCECOLUMN` 

    FROM INFORMATION_SCHEMA.`COLUMNS` info 
    JOIN INFORMATION_SCHEMA.`KEY_COLUMN_USAGE` kcu
        ON kcu.COLUMN_NAME = info.COLUMN_NAME 
        AND kcu.TABLE_NAME = info.TABLE_NAME

    JOIN INFORMATION_SCHEMA.`TABLE_CONSTRAINTS` tc 
        ON tc.CONSTRAINT_NAME = kcu.CONSTRAINT_NAME
        AND tc.TABLE_NAME = kcu.TABLE_NAME

    JOIN INFORMATION_SCHEMA.`REFERENTIAL_CONSTRAINTS` rk 
        ON rk.CONSTRAINT_NAME = tc.CONSTRAINT_NAME
        AND rk.TABLE_NAME = kcu.TABLE_NAME

    JOIN INFORMATION_SCHEMA.`KEY_COLUMN_USAGE` kcufk
        ON kcufk.CONSTRAINT_NAME = rk.UNIQUE_CONSTRAINT_NAME
        AND kcufk.TABLE_NAME = rk.TABLE_NAME

    WHERE info.TABLE_NAME = 'reportsetting' 
       AND info.TABLE_SCHEMA = 'core' 
    ORDER BY info.ORDINAL_POSITION ASC

从MySql DB中选择所有列名称

1 个答案: