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  • select into from和insert into select from两种表复制语句区别

    select into from和insert into select from两种表复制语句区别

     

    select * into target_table from source_table;

    insert into target_table(column1,column2) select column1,5 from source_table; 

    以上两句都是将源表source_table的记录插入到目标表target_table,但两句又有区别。
    第一句(select into from)要求目标表target_table不存在,因为在插入时会自动创建。
    第二句(insert into select from)要求目标表target_table存在,由于目标表已经存在,所以我们除了插入源表source_table的字段外,还可以插入常量,如例中的:5。

    例如:需要将user_city表中的部分字段值拷贝到dim_pub_county_act表中(字段名不同),则语句如下:

    INSERT
    INTO
        SUI1.DIM_PUB_COUNTY_ACT
        (
            CITY_ID,
            COUNTY_ID,
            BEGIN_TIME,
            END_TIME,
            COUNTY_NAME,
            ACTIVE_FLAG,
            AREA_CODE,
            DESC_TXT
        )
    SELECT
        parentid as city_id,
        cityid as county_id,
        '2011-08-15 00:00:00' as BEGIN_TIME,
        '2011-08-15 00:00:00'as END_TIME,
        cityname as COUNTY_NAME,
        1 as ACTIVE_FLAG,
        1 as AREA_CODE,
        '地区' as DESC_TXT
    FROM
        user_city
    WHERE
        parentid LIKE 'city1_';

    -----------------------------------------------------------------

    INSERT
    INTO
        SUI1.DIM_PUB_DEPT_ACT
        (
            DEPT_ID,
            CITY_ID,
            COUNTY_ID,
            DEPT_NAME,
            ACTIVE_FLAG,
            BEGIN_TIME,
            END_TIME,
            DESC_TXT
        )
      SELECT
       t1.cityid as dept_id,
       t2.parentid as city_id,
       t1.parentid as county_id,
       t1.cityname as dept_name,
       1 as ACTIVE_FLAG,
       '2011-08-15 00:00:00' as BEGIN_TIME,
        '2011-08-15 00:00:00'as END_TIME,
       '片区' as DESC_TXT
    FROM
        (select * from user_city where parentid like 'city101_') t1,(select * from user_city where parentid like 'city1_') t2

    WHERE t1.parentid = t2.cityid;

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  • 原文地址:https://www.cnblogs.com/dabaixiong/p/5476384.html
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