case when tt1."出_汇总" is null then 0 else ((tt1."数量")::numeric - COALESCE((tt1."出_入差异" - lag(tt1."出_入差异", 1, (0)::numeric) OVER (PARTITION BY tt1."产品代码" ORDER BY tt1."日期" NULLS FIRST, tt1."数量")),0)) end AS "数量_出", case when tt1."...
pg_type.typnameasColumnType, (case whencol.attlen<0thencol.atttypmodelsecol.attlenend)asColumnLen, (select count(*)frompg_constraint ctwherect.contype=p::charandcol.attnum =any(conkey)andct.conrelid=tbl.oid)asIsPk, (case whenseq.oidis null then0else1end)asIsAutoIncrease, (case whenc...
ISNULL()in MySQL can be adopted to make it easier to check whether a column is NULL or not. Take a look at the example below: Copy 1SELECTname, ISNULL(stock_level)ASunknown_status2FROMproducts; In this query,unknown_statuswill contain 1 ifstock_levelisNULL, and0otherwise. ThisSELECT-...
代码语言:javascript 代码运行次数:0 运行 AI代码解释 create table"t_user"("id"bigserial notnull,"username"varchar(64)notnull,constraint t_user_pk primarykey(id));insert into t_uservalues(1,'ACGkaka'); 会话一: 执行update语句。 代码语言:javascript 代码运行次数:0 运行 AI代码解释 begin;update ...
而只有单个空格的字符串是不会被转成NULL的。因为它并不是空字符串(empty string) postgresql中的NULLs和空字符串(empty string) 使用相同的表结构 postgres@=#SELECT id,content,postgres-# CASE WHEN content IS NULL THEN 1 ELSE 0 END AS isnull,postgres-# CASE WHEN content = '' THEN 1 ELSE 0 END...
Example: How to Use CASE Expression as Equivalent of ISNULL? We will utilize the same table’s column to depict the working of the CASE expression: SELECTemp_bonus,CASEWHENemp_bonusISNULLTHEN0ELSEemp_bonusENDASmodified_emp_bonusFROMemp_details; ...
第一第二个值都为null,则返回第三个不为null的值返回当前时间; 2.DECODE(); 用法1: decode(条件,值1,返回值1,值2,返回值2,...值n,返回值n,缺省值) 该函数的含义如下: IF 条件=值1 THEN RETURN(翻译值1) ELSIF 条件=值2 THEN RETURN(翻译值2) ...
如上,我们插入4条数据,一个NULL,一个空字符串,一个空格字符串和包含一个字符的字符串.下面我们看看在Oracle中的处理: SELECT id, content, CASE WHEN content IS NULL THEN 1 ELSE 0 END AS isnull, CASE WHEN content = '' THEN 1 ELSE 0 END AS isempty, ...
特殊值设置:为空或空字符串时值为0, ALTER TABLE purchase_order ALTER COLUMN payments_state SET DATA TYPE int4 USING (case when payments_state isnull or char_length(trim(payments_state)) = 0 then 0 else payments_state::int4 end), ALTER COLUMN payments_state SET DEFAULT 0; ALTER TABLE pur...
'||case when datname is null then 'NULL' else datname::text end||' , Client_Addr: '||case when client_addr is null then 'NULL' else client_addr::text end||' , Client_Port: '||case when client_port is null then 'NULL' else client_port::text end||' , Application_Name: '|...