zoukankan      html  css  js  c++  java
  • MySQL之常用SQL语句

      1) 分表之后统计数据的总量

        SELECT
            (a0.total + a1.total + a2.total + a3.total + a4.total + a5.total + a6.total + a7.total) total
        FROM
        (
            (
                SELECT
                    count(*) AS total
                FROM
                    wx_00
            ) a0,
            (
                SELECT
                    count(*) AS total
                FROM
                    wx_01
            ) a1,
            (
                SELECT
                    count(*) AS total
                FROM
                    wx_02
            ) a2,
            (
                SELECT
                    count(*) AS total
                FROM
                    wx_03
            ) a3,
            (
                SELECT
                    count(*) AS total
                FROM
                    wx_04
            ) a4,
            (
                SELECT
                    count(*) AS total
                FROM
                    wx_05
            ) a5,
            (
                SELECT
                    count(*) AS total
                FROM
                    wx_06
            ) a6,
            (
                SELECT
                    count(*) AS total
                FROM
                    wx_07
            ) a7
        );

      2. 导出整个数据库或表中的数据字典

    SELECT
        TABLE_NAME as '表名',
        COLUMN_NAME as '字段',
        COLUMN_TYPE as '数据类型',
      COLUMN_DEFAULT as '默认值',
      IS_NULLABLE as '是否为NULL', 
        COLUMN_COMMENT as '备注'
    FROM
        information_schema. COLUMNS
    WHERE
        TABLE_SCHEMA = 'jiaoni_zmt';
    
    SELECT
        TABLE_NAME as '表名',
        COLUMN_NAME as '字段',
        COLUMN_TYPE as '数据类型',
      COLUMN_DEFAULT as '默认值',
      IS_NULLABLE as '是否为NULL', 
        COLUMN_COMMENT as '备注'
    FROM
        information_schema. COLUMNS
    WHERE
        TABLE_SCHEMA = 'jiaoni_zmt' AND TABLE_NAME ='app_member';
  • 相关阅读:
    希腊字母写法
    The ASP.NET MVC request processing line
    lambda aggregation
    UVA 10763 Foreign Exchange
    UVA 10624 Super Number
    UVA 10041 Vito's Family
    UVA 10340 All in All
    UVA 10026 Shoemaker's Problem
    HDU 3683 Gomoku
    UVA 11210 Chinese Mahjong
  • 原文地址:https://www.cnblogs.com/xingxia/p/mysql_sql.html
Copyright © 2011-2022 走看看