| 求字符串长度 | LENGTH(str) | LENGTH(str) | LEN(str) | LENGTH(str) |
| 字符切割 | SUBSTR(str,index,length) | SUBSTR(str,index,length) | SUBSTRING(str,index,length) | SUBSTRING(str,index,length) |
| 字符串连接 | str1||str2||str3...strN | str1||str2||str3...strN | str1+str2+str3...strN | CONCAT(str1,str2,str3...strN) |
| 字符串索引 | INSTR(str,subStr) | strpos(str,subStr) | CHARINDEX(subStr,str) | INSTR(str,subStr) |
| 日期格式化 | TO_CHAR(date,'yyyy-mm-dd hh24:mi:ss') | TO_CHAR(date::timestamp,'yyyy-mm-dd hh24:mi:ss') | CONVERT(VARCHAR,date,20) | DATE_FORMAT(date,'%Y-%m-%d %H:%i:%s') |
| 相等判断 | decode(arg[0],arg[1],arg[2],arg[3]) | CASE WHEN arg[0]=arg[1] THEN arg[2] ELSE arg[3] END | CASE WHEN arg[0]=arg[1] THEN arg[2] ELSE arg[3] END | IF(arg[0]=arg[1],arg[2],arg[3]) |
| 数字转字符 | TO_CHAR(num) | CAST(num AS VARCHAR) | CAST(num AS VARCHAR) | CONVERT(num,CHAR) |
| 判空 | NVL(str1,str2) | COALESCE(str1,str2) | ISNULL(str1,str2) | IFNULL(str1,str2) |
| 位与运算 | BITAND(num1, num2) | num1 & num2 | num1 & num2 | num1 & num2 |
| 位或运算 | num1 + num2 - BITAND(num1, num2) | num1 | num2 | num1 | num2 | num1 | num2 |
| 数字对应的ASCII | CHR(num) | CHR(num) | CHAR(num) | CHAR(num USING ASCII) |
| 字符串左填充 | LPAD(source,padded_length,pad_string) | LPAD(source,padded_length,pad_string) | CONCAT(REPLICATE(pad_str, len-LEN(str)),str) | LPAD(source,padded_length,pad_string) |
| 获取当前日期 | SYSDATE | CURRENT_TIMESTAMP | GETDATE() | SYSDATE() |
| 字符串两端添加逗号 | ,||str||, | ,||str||, | ,+str+, | CONCAT(',',str,',') |
| 判断字符串是否为空 | str IS NULL | str='' | str='' | str='' |
| 字符串转化为日期 | TO_DATE(str,'yyyymmdd') | TO_DATE(str,'yyyymmdd') | CONVERT(DATE,str,112) | STR_TO_DATE(str,'%Y%m%d') |
| 字符串转整数 | TO_NUMBER(str) | CAST(str AS DECIMAL) | CAST(str AS DECIMAL) | CONVERT(str,DECIMAL) |
| 字符串转化为日期时间 | TO_TIMESTAMP(dateStr||' '||timeStr,'yyyyMMdd HH24:mi:ss') | TO_TIMESTAMP(...) | CONVERT(DATETIME,CONCAT(CONVERT(DATE,dateStr,112),' ',timeStr),120) | STR_TO_DATE(CONCAT(dateStr,' ',timeStr),'%Y%m%d %H:%i:%s') |
| 当前日期（整型） | TO_NUMBER(TO_CHAR(SYSDATE,'yyyymmdd')) | CAST(TO_CHAR(CURRENT_TIMESTAMP,'yyyymmdd') AS INTEGER) | CAST(CONVERT(VARCHAR,GETDATE(),112) AS INT) | CONVERT(DATE_FORMAT(SYSDATE(),'%Y%m%d'),DECIMAL) |
| 数字转化为时间间隔 | TRUNC(num/86400) || '天' || TRUNC(MOD(num,86400)/3600) || '小时' || TRUNC(MOD(num,3600)/60) || '分' || MOD(num,60) || '秒' | 同Oracle | CONCAT(FLOOR(num/86400),'天',FLOOR((num%86400)/3600),'小时',FLOOR((num%3600)/60),'分',num%60,'秒') | CONCAT(FLOOR(num/86400),'天',FLOOR(MOD(num,86400)/3600),'小时',FLOOR(MOD(num,3600)/60),'分',MOD(num,60),'秒') |
| 日期延后若干天 | args[0] + args[1] | `args[0] + (args[1] | | ’ day’)::INTERVAL` |
| 日期延后若干月 | ADD_MONTHS(args[0],args[1]) | `args[0] + (args[1] | | ’ month’)::INTERVAL` |
| 判断是否不相等 | CASE WHEN arg[0]!=arg[1] THEN arg[2] ELSE arg[3] END | 同Oracle | 同Oracle | IF(arg[0]!=arg[1],arg[2],arg[3]) |
| 日期相减获取天数 | args[0] - args[1] | EXTRACT(DAY FROM (args[0]-args[1])) | DATEDIFF(DAY,args[1],args[0]) | DATEDIFF(args[0],args[1]) |
| 空字符串检查并赋值 | CASE WHEN (str1 IS NULL OR str1='') THEN str2 ELSE str1 END | 同Oracle | 同Oracle | IF(str1 IS NULL OR str1='', str2, str1) |
| 判断字符串为NULL或空 | str IS NULL | (str IS NULL OR str='') | 同PostgreSQL | 同PostgreSQL |
| 判断字符串非NULL且非空 | str IS NOT NULL | (str IS NOT NULL AND str!='') | 同PostgreSQL | 同PostgreSQL |
