Tag: MySQL

#1093 – You can’t specify target table ‘table_name’ for update in FROM clause

Have you ever got this MySQL error? Oh! You are searching for a solution right? You have come to the right place. Let me give you the simplest answer and it works charm.

For the time being assume that this is your query.

What you can do is change the query to something like this below.

Okay let me explain how the magic happens here.

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How to do MySQL Indexing

MySQL Indexes! Whooh! Let me tell you what my experience about indexing a table. I had a SQL query which took 8-9 secs to fetch the data I want. After indexing now it only takes 1 sec. Interesting right. Let’s go through what’s indexing and how to and when to and stuff. You could find technical explanation of indexes in the internet. So let me elaborate it in a more appealing way to you.

Index is a pointer to the table and it allows you to retrieve the data faster. It’s the same as the index which we find in the back of a book. Index will represent the book in the keyword or subject order where book is printed in the page order. It’s true that index will faster your select query but it will slow down your other queries such as updates and inserts. You might be wondering why is that. It’s because once the new data is added to the table, Index should be updated too. Otherwise how can an index points to the new data in the table.

There are three types of indexes

  • Single Column(EG :- Indexed by mobile No)
  • Composite(EG :- Indexed by first name and last name)
  • Unique (EG :- indexed by e-mail)

Look at table below.

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