oracle string removal

Detailed explanation of how to remove specified characters from Oracle strings

In the Oracle database, string operations often need to be performed. One of the common requirements is to remove specified characters from the string. This article will introduce several methods for removing specified characters from strings in Oracle database.

Method 1: Replace with REPLACE function

The REPLACE function can replace some characters or character sequences in a string with another character or character sequence. Therefore, we can use the REPLACE function to remove specified characters from a string.

Assuming that we need to remove the "-" character in the string, we can use the following SQL statement:

SELECT REPLACE('123-456-789', '-', '') FROM dual;

The execution result is: 123456789

where , REPLACE('123-456-789', '-', '') means replacing the "-" character in the string 123-456-789 with an empty string , thereby achieving the purpose of removing the "-" character.

Method 2: Use the TRANSLATE function to replace

The TRANSLATE function can replace some characters in the string with other characters. Unlike the REPLACE function, the TRANSLATE function can replace multiple characters at one time, so its replacement efficiency is higher. Three parameters need to be specified when using them, namely source string, source character set and target character set.

Assuming that we need to remove the "-" character in the string, we can use the following SQL statement:

SELECT TRANSLATE('123-456-789', '-', '') FROM dual;

The execution result is: 123456789

where , TRANSLATE('123-456-789', '-', '') means replacing the "-" character in the string 123-456-789 with an empty string , thereby achieving the purpose of removing the "-" character.

Method 3: Replace with the REGEXP_REPLACE function

The REGEXP_REPLACE function can perform regular expression-based replacement operations on strings. Regular expressions provide more flexibility in matching and replacing content in strings. Suppose we need to remove the "-" character in the string, we can use the following SQL statement:

SELECT REGEXP_REPLACE('123-456-789', '-', '') FROM dual;

The execution result is: 123456789

Among them, REGEXP_REPLACE( '123-456-789', '-', '') means replacing the "-" character in the string 123-456-789 with an empty string to remove the "-" ” character purpose.

Method 4: Use the SUBSTR function to split and connect

The SUBSTR function can obtain a certain substring in the string. We can split a string into multiple substrings and then concatenate these substrings to remove specified characters.

Assuming that we need to remove the "-" character in the string, we can use the following SQL statement:

SELECT SUBSTR('123-456-789', 1, INSTR('123-456-789', '-') - 1) || SUBSTR('123-456-789', INSTR('123-456-789', '-') + 1, LENGTH('123-456-789')) FROM dual;

The execution result is: 123456789

where , SUBSTR('123-456-789', 1, INSTR('123-456-789', '-') - 1) means getting the string 123-456-789## The substring before the "-" character in #, that is, 123; SUBSTR('123-456-789', INSTR('123-456-789', '-') 1, LENGTH('123-456-789')) means getting the substring after the "-" character in the string, that is, 456-789. We concatenate the two substrings using a hyphen, thereby removing the "-" character from the original string.

This article introduces four methods for removing specified characters from strings in Oracle database, namely using the REPLACE function to replace, using the TRANSLATE function to replace, using the REGEXP_REPLACE function to replace and using the SUBSTR function to split and connect. Different methods have different characteristics and scope of application, and the appropriate method can be selected according to actual needs. Hope this article can be helpful to you.

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