concat_ws('', t.typname, SUBSTRING(format_type(a.atttypid, a.atttypmod) from '\(.*\)')) as "属性", (case when a.attnotnull = true then 1 else 0 end) as 是否非空, (case when ( select count(pg_constraint.*) from pg_constraint inner join pg_class on pg_constraint.conrelid...
SELECT date_trunc('hour', created_at) as date, CAST(COUNT(case when subscription = true then id end) AS INTEGER) as subscriptions, CAST(COUNT(case when subscription = false then id end) AS INTEGER) as unsubscriptions FROM requests GROUP BY date ORDER BY date Output: 问题是,即使表中没...
总结:substr(字段,n1,n2),从n1个字符开始,往后延n2位 (3)判断情况case when case when ... then ... when ... then ... else ... end 1. 2. 3. 4. 5. 实例: case when ppt.filetype='1' THEN NULL when ppt.filetype='0' THEN end 1. 2. 3. 4. 5. (4)判断是否包含数组中position...
判断表是否存在方法1: SELECT case WHEN a.cc =1 THEN 2 else 0 END FROM ( select count(*) as cc from pg_class where relname = 'wo' --wo is table name,pg_class是pg自带的关键字 ) as a 方法2: 用if判断,但有以下条件 TheIFstatementis part of the default procedural language PL/pgSQL...
在postgres sql中count函数可以用于哪些数据类型? postgresql的count函数如何与group by子句一起使用? PostgreSQL是一种开源的关系型数据库管理系统,它支持SQL查询语言。在PostgreSQL中,可以使用Count函数来统计查询结果集中的行数。 Count函数是一个聚合函数,用于计算指定列或表达式的非空行数。它可以用于单个表或多个表的...
判断表是否存在方法1: SELECT case WHEN a.cc =1 THEN 2 else 0 END FROM ( select count(*) as cc from pg_class where relname = 'wo' --wo is table name,pg_class是pg自带的关键字 ) as a 方法2: 用if判断,但有以下条件 TheIFstatementis part of the default procedural language PL/pgSQL...
postgresif，when及判断表是否存在的sql编写判断表是否存在⽅法1：SELECT case WHEN a.cc =1 THEN 2 else 0 END FROM (select count(*) as cc from pg_class where relname = 'wo' --wo is table name，pg_class是pg⾃带的关键字 ) as a ⽅法2：⽤if判断，但有以下条件 The ...
postgres=# select*frompg_get_wal_stats('0/157BA88','0/157E768',true)order by count_percentage desc;resource_manager/record_type|count|count_percentage|record_size|record_size_percentage|fpi_size|fpi_size_percentage|combined_size|combined_size_percentage---+---+---+---+---+---+---+...
(case when (select count(*) from pg_constraint where conrelid = a.attrelid and conkey[1]=attnum and contype='u')>0 then 'Y' else 'N' end) as U, (case when (select count(*) from pg_constraint where conrelid = a.attrelid and conkey[1]=attnum and contype='f')>0 then '...
mysql中sum与if,case when 结合使用 2019-11-28 19:15 −1.sum与if结合使用 如图:数据表中,count_money 字段可为正,可为负。为正表示收入,负表示支出。 统计总收入,总支出。 select sum(if(count_money > 0, count_money, 0)) as sum_receipt, ... ...