Type Conversion Function
Last updated: 2024-01-22 10:52:48
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 |
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. |
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. |
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).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. |
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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