MySQL common SQL optimization, mysqlsql

MySQL common SQL optimization, mysqlsql

• Avoid using where as much as possible! = Or <> operator. Otherwise, full table query is performed.

• For queries that avoid full scanning, consider creating an index on the columns involved in where or order.

• Avoid null Value Determination in where; otherwise, full table scan is performed.

• When querying, do not * query all, specify as required

• Use In and not in with caution. Otherwise, full table scan may occur.

• Do not write meaningless queries

• When creating an index, it depends on the situation. It is recommended that there be no more than 6 indexes in a table.

• Try to use varchar to replace char

• Use table variables instead of temporary tables whenever possible

• Avoid returning big data to the client. If the data volume is too large, consider whether the corresponding requirements are reasonable.

• Avoid large transaction operations and improve system concurrency