Function: Returns the logarithm of the input value with base
Output Data Type: DOUBLE.
Input: applies to value of all types except timestamp, binary, nchar, and bool. Can not apply to tag column of super table.
Embedded Query Support: Both Outer Query and Inner Query
Notes：
If input value is NULL, the output value is NULL.
It is a scalar function and can not be used together with aggregate function
Applies to columns of normal table, child table and super table
-**ABS**
```mysql
SELECT ABS(field_name) FROM { tb_name | stb_name } [WHERE clause]
```
Function: Returns the absolute value of the input value
Output Data Type: If the input data is an integer numeric value, the output data type is ubigint. If the input data is a float or double value, the output data type is double
Input: applies to value of all types except timestamp, binary, nchar, and bool. Can not apply to tag column of super table.
Embedded Query Support: Both Outer Query and Inner Query
Notes：
If input value is NULL, the output value is NULL.
It is a scalar function and can not be used together with aggregate function
Applies to columns of normal table, child table and super table
-**SQRT**
```mysql
SELECT SQRT(field_name) FROM { tb_name | stb_name } [WHERE clause]
```
Function: Returns the square root value of the input value
Output Data Type: DOUBLE.
Input: applies to value of all types except timestamp, binary, nchar, and bool. Can not apply to tag column of super table.
Embedded Query Support: Both Outer Query and Inner Query
Notes：
If input value is NULL, the output value is NULL.
It is a scalar function and can not be used together with aggregate function
Applies to columns of normal table, child table and super table
-**CAST**
```mysql
SELECT CAST(expression AS type_name) FROM { tb_name | stb_name } [WHERE clause]
```
Function: Converts a value into as a specific data type of type_name.
Output Data Type: type_name specificied. Supported types include BIGINT, BINARY(N), TIMESTAMP and NCHAR(N) and BIGINT UNSIGNED
Input: Normal column, constant, scalar function and the arithmetic computation(+,-,*,/,%) among them. Input data type includes BOOL, TINYINT, SMALLINT, INT, BIGINT, FLOAT, DOUBLE, BINARY(M), TIMESTAMP, NCHAR(M), TINYINT UNSIGNED, SMALLINT UNSIGNED, INT UNSIGNED, and BIGINT UNSIGNED
Notes:
Reports error for unsupported cast
It is a scalar function and its output is NULL for input NULL
Function: Returns the string from concatenating the arguments with separator.
Output Data Type: With binary inputs, the output data type is binary. With nchar inputs, the output data type is nchar.
Input: all inputs shall be of data type binary or nchar. Can not apply to tag columns.
Notes:
Returns NULL when the separator is NULL. If the separator is not NULL and all the other string values are NULL, the result is an empty string.
The function takes 3 to 9 string values as input. all inputs must be of the same data type.
This function applies to normal table, child table and super table
This function applies to bother out query and inner query
-**LENGTH**
```
SELECT LENGTH(str|column) FROM { tb_name | stb_name } [WHERE clause]
```
Function: Returns the length of the string measure in bytes
Output Data Type: INT。
Input: BINARY or NCHAR values. Can not apply to tag columns
Notes:
Returns NULL when input is NULL.
This function applies to normal table, child table and super table
This function applies to bother out query and inner query
-**CHAR_LENGTH**
```
SELECT CHAR_LENGTH(str|column) FROM { tb_name | stb_name } [WHERE clause]
```
Function: Returns the length of the string measure in characters
Output Data Type: INT。
Input: BINARY or NCHAR values. Can not apply to tag columns
Notes:
Returns NULL when input is NULL.
This function applies to normal table, child table and super table
This function applies to bother out query and inner query
-**LOWER**
```
SELECT LOWER(str|column) FROM { tb_name | stb_name } [WHERE clause]
```
Function: Returns the lower case of input value
Output Data Type: BINARY or NCHAR. Same data type as Input.
Input: BINARY or NCHAR values. Can not apply to tag columns
Notes:
Returns NULL when input is NULL.
This function applies to normal table, child table and super table
This function applies to bother out query and inner query
-**UPPER**
```
SELECT UPPER(str|column) FROM { tb_name | stb_name } [WHERE clause]
```
Function: Returns the upper case of input value
Output Data Type: BINARY or NCHAR. Same data type as Input.
Input: BINARY or NCHAR values. Can not apply to tag columns
Notes:
Returns NULL when input is NULL.
This function applies to normal table, child table and super table
This function applies to bother out query and inner query
-**LTRIM**
```
SELECT LTRIM(str|column) FROM { tb_name | stb_name } [WHERE clause]
```
Function: removes leading spaces from a string
Output Data Type: BINARY or NCHAR. Same data type as Input.
Input: BINARY or NCHAR values. Can not apply to tag columns
Notes:
Returns NULL when input is NULL.
This function applies to normal table, child table and super table
This function applies to bother out query and inner query
-**RTRIM**
```
SELECT RTRIM(str|column) FROM { tb_name | stb_name } [WHERE clause]
```
Function: removes trailing spaces from a string
Output Data Type: BINARY or NCHAR. Same data type as Input.
Input: BINARY or NCHAR values. Can not apply to tag columns
Notes:
Returns NULL when input is NULL.
This function applies to normal table, child table and super table
This function applies to bother out query and inner query
-**SUBSTR**
```
SELECT SUBSTR(str,pos[,len]) FROM { tb_name | stb_name } [WHERE clause]
```
Function: extracts substring from a string str, starting from pos and extracting len characters.
Output Data Type: BINARY or NCHAR. Same data type as Input.
Input: BINARY or NCHAR values. Can not apply to tag columns
Notes:
Returns NULL when input is NULL.
Input pos can be negative or positive. If it is a positive number, this function extracts from the beginning of the string. If it is a negative number, this function extracts from the end of the string
If input len is ommited, the output is whole substring starting from pos.
This function applies to normal table, child table and super table
This function applies to bother out query and inner query
