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