关于select count()
来源:百度知道 编辑:UC知道 时间:2024/05/21 07:26:16
1、首先想知道select count(*) from 的from后面是不是只可以跟一个表名?
2、下面的语句是从两个表中检索的SQL文,请问如何取得其检索结果的条数,也就是用select count(*)该怎么写?望高手指点!
SELECT
STM_MITSUMORI_JOKEN_PATTERN.MITSUMORI_JOKEN_PAT_NO
,STM_MITSUMORI_JOKEN_PATTERN.MITSUMORI_JOKEN_PAT_NM
,STM_MITSUMORI_JOKEN_PATTERN.BIKO
,STM_TORIHIKISAKI.TORIHIKISAKI_CODE
,STM_TORIHIKISAKI.TORIHIKISAKI_NM
FROM
STM_MITSUMORI_JOKEN_PATTERN A
,STM_TORIHIKISAKI B
WHERE
STM_MITSUMORI_JOKEN_PATTERN.RIYO_KIGYO_CODE=#riyo_Kigyo_Code#
<isNotEmpty property="mitsumori_Joken_Pat_No_From">
AND A.MITSUMORI_JOKEN_PAT_NO >= #mitsumori_Joken_Pat_No_From#
</isNotEmpty>
<isNotEmpty property="mitsumori_Joken_Pat_No_To">
AND A.MITSUMORI_JOKEN_PAT_NO <= #mitsumori_Joken_Pat_No_To#
</isNotEmpty>
<isNotEmpty property="mitsumori_Joken_Pat_Nm">
AND A.MITSUMORI_JOKEN_PAT_NM like #mitsumori_Joken_Pat_Nm#
2、下面的语句是从两个表中检索的SQL文,请问如何取得其检索结果的条数,也就是用select count(*)该怎么写?望高手指点!
SELECT
STM_MITSUMORI_JOKEN_PATTERN.MITSUMORI_JOKEN_PAT_NO
,STM_MITSUMORI_JOKEN_PATTERN.MITSUMORI_JOKEN_PAT_NM
,STM_MITSUMORI_JOKEN_PATTERN.BIKO
,STM_TORIHIKISAKI.TORIHIKISAKI_CODE
,STM_TORIHIKISAKI.TORIHIKISAKI_NM
FROM
STM_MITSUMORI_JOKEN_PATTERN A
,STM_TORIHIKISAKI B
WHERE
STM_MITSUMORI_JOKEN_PATTERN.RIYO_KIGYO_CODE=#riyo_Kigyo_Code#
<isNotEmpty property="mitsumori_Joken_Pat_No_From">
AND A.MITSUMORI_JOKEN_PAT_NO >= #mitsumori_Joken_Pat_No_From#
</isNotEmpty>
<isNotEmpty property="mitsumori_Joken_Pat_No_To">
AND A.MITSUMORI_JOKEN_PAT_NO <= #mitsumori_Joken_Pat_No_To#
</isNotEmpty>
<isNotEmpty property="mitsumori_Joken_Pat_Nm">
AND A.MITSUMORI_JOKEN_PAT_NM like #mitsumori_Joken_Pat_Nm#
可以跟多个表名,但要用join连接起来,如
select count(*) from ta full join tb on ta.id=tb.id
select count(*) from 的from后面可以只跟一个表名
它统计的是结果集中至少包含一个非NULL值的行数
就是统计不全是NULL值的行数
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