postgres=# select round( cast ( 1 as numeric )/ cast( 4 as numeric),2); round --- 0.25 (1 row) --4 关于 cast 函数的用法 substr 索引默认为1 下面是从 第3位开始,截取1位 postgres=# SELECT substr(CAST (1234 AS text), 3,1); substr --- 3 (1 row) 1. 2. 3. 4. 5. 6. ...
类型转换函数用于将数据从一种类型转换为另一种类型。其中，CAST ( expr AS data_type ) 函数用于将表达式转换为指定数据类型，使用运算符 (::)也能实现相同功能。使用 to_date(string, format) 函数，我们可以将字符串转换为日期格式，并通过 format 参数指定日期的格式。例如，YYYY 表示4位数的年，...
and passing the resulting string to the input function of the target data type. In many common cases, this feature avoids the need to write a separate cast function for conversion. An I/O conversion cast acts the same as a regular function-based cast; only the implementation is different. ...
You can define a cast as an I/O conversion cast by using the WITH INOUT syntax. An I/O conversion cast is performed by invoking the output function of the source data type, and passing the resulting string to the input function of the target data type. In many common cases, this...
11、,从第8个字符开始截取2个字符:结果是12select cast(substring('1234abc12',8,2) as integer)-使用to_number函数来转换成整数-to_number(text, text) 返回的类型 numeric 把字串转换成numeric to_number('12,454.8-', '99G999D9S')select to_number('12121','999999999')用于数值 12、格式化的模板模...
SELECT CAST ('A15' AS INTEGER); SQL 错误 [22P02]: 错误: 无效的类型 integer 输入语法: "A15" 位置:14 to_date 函数 to_date(string, format) 函数用于将字符串 string 按照 format 格式转换为日期类型。 SELECT to_date('2020/03/15','YYYY/MM/DD'); to_date | ---| 2020-03-15| 其中,YY...
在编程中，有时我们需要将数字转换为字母，例如将数字表示的年份转换为对应的字母表示，或者将数字编码...
CreateCastStmt CreateDomainStmt CreateExtensionStmt CreateGroupStmt CreateOpClassStmt CreateOpFamilyStmt AlterOpFamilyStmt CreatePLangStmt CreateSchemaStmt CreateSeqStmt CreateStmt CreateStatsStmt CreateTableSpaceStmt CreateFdwStmt CreateForeignServerStmt CreateForeignTableStmt CreateAssertStmt CreateTransformStmt ...
str := “123” // string 转 int i, err := strconv.Atoi(str) if err == nil { ...
PostgreSQL类型转换 1.int装string select CAST (1234 AS text) selectto_char(1234,’999‘) 2.string转int selectcast('999'as NUMERIC) --5 附: PostgreSQL 类型转换函数