Oracle determines whether it is a number

In the Oracle database, determining whether it is a number can be achieved by using regular expressions or using its own built-in functions.

Method 1: Use regular expressions

Oracle provides the regexp_like function, which uses regular expressions to determine whether a string matches the specified pattern. We can use this function to determine whether a string is a number, as follows:

SELECT CASE WHEN REGEXP_LIKE('123', '^[[:digit:]]+$') THEN 1 ELSE 0 END AS is_number FROM dual;

Among them, ^ means matching the beginning of the string, $ means matching the end of the string, [[:digit:]] means matching A number between 0 and 9 means matching the previous content one or more times. If the function returns 1, it means the string is a number; if it returns 0, it means the string is not a number.

Method 2: Use built-in functions

Oracle provides some built-in functions to determine the type of a string, as shown in the following table:

##IS_NUM Determine whether the string is a number and return TRUE or FALSEIS_ALPHA Determine whether the string is a pure letter, return TRUE or FALSEIS_ALPHANUM Determine the string Whether it is a combination of letters and numbers, return TRUE or FALSEIS_ASCII Determine whether the string is entirely composed of ASCII characters, return TRUE or FALSEIS_BLANK Determine whether the string is a space, return TRUE or FALSEIS_GRAPHDetermine whether the string is acceptable Print characters, return TRUE or FALSE##IS_PRINTUse these functions to determine whether a string is a number. You can use the IS_NUM function, as follows:

Function name	Description
Determine whether the string is printable characters or spaces, return TRUE or FALSE

SELECT CASE WHEN IS_NUM('123') THEN 1 ELSE 0 END AS is_number FROM dual;

If the function returns TRUE, it means that the string is a number; if it returns FALSE, it means a character Strings are not numbers.

Summary

In Oracle, determining whether a string is a number can be achieved using regular expressions or built-in functions. When using regular expressions, you can use the regexp_like function to judge. When using built-in functions, you can use the IS_NUM function to determine. No matter which method is used, the string type judgment can be completed, which is convenient for developers to proceed with the next step.

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