LEFT (Azure Cosmos DB)LEFT (Azure Cosmos DB)

适用于: SQL API

返回具有指定字符数的字符串的左侧部分。Returns the left part of a string with the specified number of characters.

语法Syntax

LEFT(<str_expr>, <num_expr>)  

参数Arguments

str_exprstr_expr
要从中提取字符的字符串表达式。Is the string expression to extract characters from.

num_exprnum_expr
是指定字符数的数值表达式。Is a numeric expression which specifies the number of characters.

返回类型Return types

返回一个字符串表达式。Returns a string expression.

示例Examples

以下示例根据不同的长度值返回“abc”的左侧部分。The following example returns the left part of "abc" for various length values.

SELECT LEFT("abc", 1) AS l1, LEFT("abc", 2) AS l2 

下面是结果集。Here is the result set.

[{"l1": "a", "l2": "ab"}]  

备注Remarks

此系统函数将从范围索引中获益。This system function will benefit from a range index.

后续步骤Next steps