PostgreSQL是一种开源的关系型数据库管理系统,它支持广泛的数据类型和功能,被广泛用于各种应用场景。在PostgreSQL中,可以使用case语句在select查询中对列进行条件判断和转换。 case语句是一种条件表达式,它允许根据条件的不同返回不同的值。在select查询中,可以使用case语句对列进行条件判断,并根据条件返回不同的值或执行...
SELECT CASE语句是一种在数据库中使用的条件选择语句,它可以根据不同的条件执行不同的操作。在使用PostgreSQL pg和Node编写SELECT CASE语句时,可以按照以下步骤进行: 导入必要的模块和库:在Node.js中,可以使用pg库来连接和操作PostgreSQL数据库。首先需要安装pg库,然后在代码中导入相应的模块。 导入必要的模块和库:...
CASE selector WHEN selector_value_1 THEN statements_1 WHEN selector_value_1 THEN statement_2 ... ELSE else_statements END CASE; Code language: PostgreSQL SQL dialect and PL/pgSQL (pgsql) Let’s examine the syntax of the simple CASE statement in detail: 1) selector The selector is an...
PostgreSQL , adhoc查询 , 大宽表 , 任意字段组合查询 , 索引 , btree , gin , rum 背景 大宽表,任意字段组合查询,透视。是实时分析系统中的常见需求: 1、实时写入。 2、实时任意字段组合查询、透视。 PostgreSQL中,有多种方法支持这种场景: 《PostgreSQL 9种索引的原理和应用场景》 1、方法1,每个字段加一个...
PostgreSQL条件表达式 case when then end 例: SELECT CASE WHEN (store_size <= (100)::NUMERIC) THEN '小店'::TEXT WHEN (store_size >= (200)::NUMERIC) THEN '大店'::TEXT ELSE '中店'::TEXT END AS store_area_level FROM SALE
After restoring the database, you can view the table in thepgAdmininterface which comes with the default installation of PostgreSQL. Upon running a simpleSELECTstatement, you get to know about the columns, their data-types and also the rows the table is containing - ...
How to work with control structures in PostgreSQL stored procedures: Using IF, CASE, and LOOP statements Arun Gavhane January 19, 2023 Stored procedures in PostgreSQL are ones that define a function for creating triggers or custom functions. There are three main types of co...
The CASE statement comes in two flavors: the first evaluates one or more conditions and returns the result for the first condition that is true. If no condition is true, the result after ELSE is returned, or NULL if there is no ELSE part: ...
select_random_ranges.lua Add libAttachSQL driver to Sysbench 2 years ago update_index.lua Change lua scripts to 'require common' if a testdir wasn't passed a month ago update_non_index.lua Change lua scriptsto'require common'ifa testdir wasn't passed a month ago ...
postgreSQL 应用case when的例子 select name, md5(indvl_id_nbr) as indvl_id_nbr, case when char_length(indvl_id_nbr)=18 or char_length(indvl_id_nbr)=15 then substring(indvl_id_nbr from 1 for 6) end as id_prefix, case when char_length(indvl_id_nbr)=18 then substring(indvl_id...