Type Conversion Functions_SQL Functions_Log Search and Analysis (Pipe Character)_User Guide

Function List

**Table 1** Type conversion functions
Function	Description
cast	Converts a value from one data type to another and adds the data type to dynamic parameters. If a value fails to be converted, the query operation is terminated and an exception is thrown.
try_cast	Converts a value from one data type to another and adds the data type to dynamic parameters. If a value fails to be converted, the exception is captured and the value is returned as null.
typeof	Data type of the specified field.

cast

This function converts a value from one data type to another and provides the data type to dynamic parameters.

The conversion expressions can be used wherever expressions are allowed.

Syntax: CAST(Expression as Datatype)

**Table 2** Parameter description
Parameter	Description	Type	Mandatory
expression	Source type of the expression.	Any	Yes
Datatype	Target type.	SQL data type, such as bigint, varchar, double, double precision, boolean, timestamp, decimal, integer, char, or date	Yes

**Table 3** Mapping between index and SQL data types
Index Data Type	SQL Data Type
Long	Bigint
String	Varchar
Float	Double or double precision

Return value type: target data type

Example: select cast(time as date)

**Table 4** Query and analysis results
Type	Query Statement	Returned Result
Scenario	cast(time as date)	2023-08-31 23:11:17.000

try_cast

Converts a value from one data type to another and adds the data type to dynamic parameters. If a value fails to be converted, the exception is captured and the value is returned as null.

Syntax: TRY_CAST(Expression as Datatype)

The final data type upon conversion is the target type. The data type that needs to be converted is the source type.

**Table 5** Parameter description
Parameter	Description	Type	Mandatory
expression	Source type.	Any	Yes
Datatype	Target type.	SQL data type, such as bigint, varchar, double, double precision, boolean, timestamp, decimal, integer, char, or date	Yes

Return value type: target data type

Example: select try_cast(time as date)

**Table 6** Query and analysis result
Type	Scenario
Query statement	try_cast(time as date)
Returned result	null

typeof

Returns the data type of a specified field or expression.

Syntax: typeof(expression)

**Table 7** Parameter description
Parameter	Description	Type	Mandatory
expression	Field or expression whose result type is to be determined.	Any	Yes

Return value type: target data type

Example: select typeof(from_unixtime(__time)) as t

**Table 8** Query and analysis result
Type	Scenario
Query statement	typeof(from_unixtime(__time))
Returned result	timestamp(3) with time zone

Type Conversion Functions

Function List

cast

try_cast

typeof

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