How to use SUBSTRING_INDEX in MySQL

In MySQL database operations, string processing is an inevitable link. The SUBSTRING_INDEX function is designed for this, which can efficiently extract substrings based on separators.

SUBSTRING_INDEX function application example

The following example shows the flexibility and practicality of the SUBSTRING_INDEX function:

Extract specific parts from URL

For example, extract the domain name:

 <code class="sql">SELECT SUBSTRING_INDEX('www.mysql.com', '.', 2);</code>

Extract file extensions

Easily get file extensions:

 <code class="sql">SELECT SUBSTRING_INDEX('file.pdf', '.', -1);</code>

Handle the case of non-existent delimiters

If the delimiter does not exist, the function returns the original string:

 <code class="sql">SELECT SUBSTRING_INDEX('example.com', '?', 1);</code>

FAQ

How common is SUBSTRING_INDEX function?

This function is unique to MySQL database.

How do SQL Server and PostgreSQL implement similar functions?

SQL Server can use CHARINDEX , LEFT and RIGHT functions in combination; PostgreSQL depends on POSITION and other functions.

What are the advantages of SUBSTRING_INDEX function?

It simplifies substring extraction based on delimiters and improves string processing efficiency.

Can SUBSTRING_INDEX function handle duplicate separators?

Yes, the split position is controlled by specifying the number of occurrences.

Summarize

SUBSTRING_INDEX is a powerful string operation function in MySQL database. It can efficiently handle various delimiter-based string extraction tasks and is an indispensable practical tool in daily database operations. For more details, please refer to the "Complete Guide for SUBSTRING_INDEX in SQL".

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