How Can I Replace or Delete Multiple Strings in a MySQL Field?

Multiple String Replacement and Deletion in MySQL

Replacing and deleting multiple strings in a MySQL field can be achieved using a combination of techniques:

Chaining REPLACE Functions

MySQL's REPLACE function can be used to replace single strings. By chaining multiple REPLACE functions, you can replace several strings in sequence:

select replace(replace('hello world','world','earth'),'hello','hi')

This example replaces "world" with "earth" and then replaces "hello" with "hi", resulting in "hi earth."

Subqueries

Subqueries allow you to perform a nested query and use its results as input to the outer query. Using a subquery, you can replace multiple strings in a single statement:

select replace(london_english,'hello','hi') as warwickshire_english
from (
    select replace('hello world','world','earth') as london_english
) sub

This query replaces "hello" with "hi" in the result of a subquery that replaces "world" with "earth."

JOINs

JOINs can also be used to replace multiple strings. In this approach, you create a table with the original strings and another table with the replacement strings. You then perform an INNER JOIN and use the JOIN condition to match the strings that need to be replaced:

select group_concat(newword separator ' ')
from (
    select 'hello' as oldword
    union all
    select 'world'
) orig
inner join (
    select 'hello' as oldword, 'hi' as newword
    union all
    select 'world', 'earth'
) trans on orig.oldword = trans.oldword

This query will produce a comma-separated list of replacement strings based on the JOIN condition.

By leveraging these techniques, you can effectively replace or delete multiple characters or strings in a MySQL field.

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