MySQL的SQL语句写法，除了那些基本的之外，还有一些也算比较常用的，这里记录下来，以便以后查找。

好记性不如烂笔头，这话说的太有道理了，一段时间不写它，还真容易忘记，本文只是一篇笔记而已。

1.将数据从T1表导入到T2表

INSERT INTO T2 (C1,C2) SELECT C1,C2 FROM T1 [WHERE C1 = XX AND C2 = XX ORDER BY C1]

2.使用T2表的NAME来更新T1表的NAME

UPDATE T1 AS A, T2 AS B SET A.NAME = B.NAME WHERE A.TID = B.ID

3.两表的关联更新

UPDATE T_ROLE_USER AS A,
 (
    SELECT
        ID
    FROM
        T_USER
    WHERE
        DEPARTID IN (
            SELECT
                ID
            FROM
                T_DEPART
            WHERE
                LENGTH(ORG_CODE) = 9
        )
) AS B
SET A.ROLEID = '123456'
WHERE
    A.USERID = B.ID

4.自己和自己关联更新

UPDATE T_DEPART AS A,
 (
    SELECT
        ID,
        SUBSTRING(ORG_CODE, 1, 6) ORG_CODE
    FROM
        T_DEPART
    WHERE
        LENGTH(ORG_CODE) = 8
    AND PARENT_DEPART_ID IS NOT NULL
) AS B
SET A.PARENT_DEPART_ID = B.ID
WHERE
    SUBSTRING(A.ORG_CODE, 1, 6) = B.ORG_CODE

5.两表关联删除，将删除两表中有关联ID并且T2表NAME为空的两表记录

DELETE A,B FROM T1 AS A LEFT JOIN T2 AS B ON A.TID = B.ID WHERE B.NAME IS NULL

6.将统计结果插入到表

INSERT INTO SE_STAT_ORG (
    RECORD_DATE,
    ORG_ID,
    ORG_NAME,
    SIGN_CONT_COUNT,
    SIGN_ARRI_CONT_COUNT,
    SIGN_CONT_MONEY,
    SIGN_ARRI_CONT_MONEY,
    TOTAL_ARRI_CONT_COUNT,
    TOTAL_ARRI_MONEY,
    PUBLISH_TOTAL_COUNT,
    PROJECT_COUNT
) SELECT
    *
FROM
    (
        SELECT
            '2012-06-09' RECORD_DATE,
            PARENT_ORG_ID,
            PARENT_ORG_NAME,
            SUM(SIGN_CONT_COUNT) SIGN_CONT_COUNT,
            SUM(SIGN_ARRI_CONT_COUNT) SIGN_ARRI_CONT_COUNT,
            SUM(SIGN_CONT_MONEY) SIGN_CONT_MONEY,
            SUM(SIGN_ARRI_CONT_MONEY) SIGN_ARRI_CONT_MONEY,
            SUM(TOTAL_ARRI_CONT_COUNT) TOTAL_ARRI_CONT_COUNT,
            SUM(TOTAL_ARRI_MONEY) TOTAL_ARRI_MONEY,
            SUM(PUBLISH_TOTAL_COUNT) PUBLISH_TOTAL_COUNT,
            SUM(PROJECT_COUNT) PROJECT_COUNT,
        FROM SE_STAT_USER
        WHERE DATE_FORMAT(RECORD_DATE, '%Y-%m-%d') = '2012-06-09'
        GROUP BY PARENT_ORG_ID
    ) M

7. 三表关联更新

UPDATE SE_STAT_USER A,
 (
    SELECT
        USER_ID,
        SUM(INVEST_ORG_COUNT + FINANCIAL_ORG_COUNT + INTERMEDIARY_ORG_COUNT + ENTERPRISE_COUNT) AS COMMON_COUNT
    FROM SE_STAT_USER
    WHERE DATE_FORMAT(RECORD_DATE, '%Y-%m-%d') = '2012-06-09'
    GROUP BY USER_ID
) B,
 (
    SELECT
        USER_ID,
        SUM(ESTABLISH_COUNT + STOCK_COUNT + MERGER_COUNT + ACHIEVE_COUNT) AS PROJECT_COUNT
    FROM SE_STAT_USER
    WHERE DATE_FORMAT(RECORD_DATE, '%Y-%m-%d') = '2012-06-09'
    GROUP BY USER_ID
) C
SET A.COMMON_COUNT = B.COMMON_COUNT, A.PROJECT_COUNT = C.PROJECT_COUNT
WHERE A.USER_ID = B.USER_ID
AND A.USER_ID = C.USER_ID
AND DATE_FORMAT(A.RECORD_DATE, '%Y-%m-%d') = '2012-06-09'

8.带条件的关联更新

UPDATE SE_STAT_USER A,
 (
    SELECT
        P.CHANNEL,
        COUNT(P.CONT_ID) AS CONT_COUNT,
        C.CUST_MGR_ID
    FROM
        (
            SELECT
                CHANNEL,
                CONT_ID
            FROM SK_PROJECT
            WHERE PROJECT_STATUS = 6
            AND DATE_FORMAT(AUDIT_TIME, '%Y-%m-%d') = '2012-06-11'
        ) p
    INNER JOIN SE_CONTRACT C ON P.CONT_ID = C.CONT_ID
    GROUP BY P.CHANNEL, C.CUST_MGR_ID
) B
SET
    A.STOCK_COUNT = CASE WHEN B.CHANNEL = 2 THEN B.CONT_COUNT ELSE 0 END,
    A.ESTABLISH_COUNT = CASE WHEN B.CHANNEL = 3 THEN B.CONT_COUNT ELSE 0 END,
    A.ACHIEVE_COUNT = CASE WHEN B.CHANNEL = 4 THEN B.CONT_COUNT ELSE 0 END, 
    A.BRAND_COUNT = CASE WHEN B.CHANNEL = 5 THEN B.CONT_COUNT ELSE 0 END,
    A.MERGER_COUNT = CASE WHEN B.CHANNEL = 6 THEN B.CONT_COUNT ELSE 0 END
WHERE
    A.USER_ID = B.CUST_MGR_ID
AND DATE_FORMAT(A.RECORD_DATE, '%Y-%m-%d') = '2012-06-11'

9. 加索引

ALTER TABLE PROJECT ADD INDEX INDEX_USER_ID (USER_ID),
        ADD INDEX INDEX_PROJECT_STATUS (PROJECT_STATUS);

10.删除列