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Glossary

Type Conversion Function

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Last updated: 2026-05-21 11:26:43

This document introduces the basic syntax and examples of type conversion functions.
If you need to distinguish more detailed data types when querying and analyzing data, you can use type conversion functions for data type conversion in query and analysis statements.
Function
Syntax
Description
Function cast
cast(x as type)
Parses the data type of x.
During cast execution, if a value fails to be parsed, the system terminates the entire query and analysis operation.
Function try_cast
try_cast(x as type)
Parses the data type of x.
During try_cast execution, if a value fails to be parsed, the system returns NULL and continues processing by skipping the value.
typeof
typeof(x)
Returns the data type of x.
Note: 
When dirty data may exist in logs, you are advised to use the try_cast function to avoid query and analysis failures caused by dirty data.
Function cast
The cast function is used to parse the data type of x. During cast execution, if a value fails to be parsed, the system terminates the entire query and analysis operation.
Syntax
cast(x as type)
Parameter description
Parameter
Description
x
The parameter value can be of any type.
type
SQL data type. Valid values: bigint, varchar, double, boolean, timestamp, decimal, array, or map.
For the mappings between index and SQL data types, please see Appendix: Data Type Mappings.
Note:
If type is timestamp, x must be a timestamp in milliseconds (such as 1597807109000) or a time string in the ISO 8601 time format (such as 2019-12-25T16:17:01+08:00).
When a UNIX timestamp is converted to a timestamp, the UTC+0 time zone is used by default. To convert to other time zones, you can use a function with a specified time zone feature (for example, from_unixtime(__TIMESTAMP__/1000, 'Asia/Shanghai')) or manually add a time zone offset (for example, cast(__TIMESTAMP__+8*60*60*1000 as timestamp) or cast(__TIMESTAMP__ as timestamp)+ INTERVAL 8 HOUR).
Return value type
The return value type is determined by the type parameter.
Example
1. Parse the numeric value 0.01 into a BIGINT value:
* | select cast(0.01 as bigint)
2. Convert the CLS log collection time __TIMESTAMP__ to TIMESTAMP.
* | select cast(__TIMESTAMP__ as timestamp)
Function try_cast
The try_cast function is used to parse the data type of x. During try_cast execution, if a value fails to be parsed, the system returns NULL and continues processing by skipping the value.
Syntax
try_cast(x as type)
Parameter description
Parameter
Description
x
The parameter value can be of any type.
type
SQL data type. Valid values: bigint, varchar, double, boolean, timestamp, decimal, array, or map.
For the mappings between index and SQL data types, please see Appendix: Data Type Mappings.
Return value type
The return value type is determined by the type parameter.
Example
Parse the remote_user field value into a VARCHAR value:
* | select try_cast(remote_user as varchar)
Appendix: Data Type Mappings
The mappings between index and SQL data types are as follows:
Index Data Type
SQL Data Type
long
bigint
text
varchar
double
double
json
varchar
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Cloud Log Service

Type Conversion Function

Function cast

Syntax

Parameter description

Return value type

Example

Function try_cast

Syntax

Parameter description

Return value type

Example

Appendix: Data Type Mappings

Help and Support

Function	Syntax	Description
Function cast	cast(x as type)	Parses the data type of `x`. During `cast` execution, if a value fails to be parsed, the system terminates the entire query and analysis operation.
Function try_cast	try_cast(x as type)	Parses the data type of `x`. During `try_cast` execution, if a value fails to be parsed, the system returns `NULL` and continues processing by skipping the value.
typeof	typeof(x)	Returns the data type of `x`.

Parameter	Description
x	The parameter value can be of any type.
type	SQL data type. Valid values: `bigint`, `varchar`, `double`, `boolean`, `timestamp`, `decimal`, `array`, or `map`. For the mappings between index and SQL data types, please see Appendix: Data Type Mappings.

Index Data Type	SQL Data Type
long	bigint
text	varchar
double	double
json	varchar