1selectCOUNT(distinct Tname)ascount2from Teacher3where Tname like'李%' 1. 2. 3. (5)查询没学过“叶平”老师课的同学的学号、姓名; AI检测代码解析 1select s.S#,s.Sname2from Student s3where s.S# not in4(5selectdistinct(sc.S#) from SC sc,Course c,Teacher t6where sc.C#=c.C# and ...
SELECT id, body, xxx? AS the_url, COUNT(DISTINCT(the_url)) as count FROM messages WHERE body LIKE '%://%' GROUP BY the_url; 我如何做到这一点?发布于 6 月前 ✅ 最佳回答: 您可以使用FILTER和count(*)组合来计算表中有多少记录包含某个模式,例如。 SELECT count(*) FILTER (WHERE body...
ORDER BY排序查询: DISTINCT 去重: GROUP BY 分组: HAVING 子句(与GROUP BY子句组合使用,用于选择函数结果满足某些条件的特定行): LIKE 匹配: ‘_’表示匹配一个占位符 , ’%’表示匹配任意多个字符 IN 、NOT IN、BETWEEN 与 WHERE 连用 IN:指定条件满足IN条件 NOT IN:指定条件否定IN条件 BETWEEN:以从两个指...
SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] * | expression [ AS output_name ] [, ...] INTO [ TEMPORARY | TEMP ] [ TABLE ] new_table [ FROM from_item [, ...] ] [ WHERE condition ] [ GROUP BY expression [, ...] ] [ HAVING condition [, ...] ] [ {...
(SELECT DISTINCT(final.gid) AS id, final.gname as name FROM final ORDER BY final.gname) WHEN 2 THEN (SELECT DISTINCT(final.pid) AS id, final.pname as name FROM final WHERE final.gid = $1 ORDER BY final.pname) WHEN 3 THEN (SELECT DISTINCT(final.did) AS id, final.name as name...
PSQL是指PostgreSQL,是一个功能强大的开源关系型数据库管理系统。在使用PSQL进行文本字段的查找和计数时,可以借助以下几个关键词和函数来实现: 1. `LIKE`关键词:用于模糊匹配文本...
sql := 'SELECT DISTINCT ',col_name,' FROM (',query,') q ORDER BY 1'; EXECUTE sql INTO cols; --构建纵向列的数组 sql := 'SELECT ARRAY[''',ARRAY_TO_STRING(cols, ''','''),''']'; EXECUTE sql INTO col_values; --生成结果 sql := 'SELECT ',row_name,', ARRAY[',ARRAY_TO_...
从OracleDatabase 12c第2版（12.2）开始，可以在尚未指定为 INMEMORY 的对象的列级别指定 INMEMORY ...
【case 1】项目背景:需要返回一些GC的统计数据。相关数据存在frame这张表内,表中的数据一行就是一帧的数据,可以理解为记录了这一帧内的性能信息。与需求相...
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