1- Remove duplicate values using 'DISTINCT' key in mysql query, if it is present in table. 2- Check whether the value is present in table or not using PHP and Mysql before inserting data into the ...

Learn how to write better SQL queries that are clear, accurate, and fast. Avoid common SQL query mistakes like inconsistent naming, SELECT *, parentheses, NULL values, and untested queries.

How to Check for Duplicates Before Inserting Into SQL. ... VALUES ('1','a') ON DUPLICATE KEY UPDATE column1='1', column2='a';" Run your modified query in your SQL browser to view the results.

Learn how to avoid errors, performance issues, and confusion in your SQL queries by avoiding six common join pitfalls, such as wrong join type, missing join condition, and poor formatting.