How to optimize queries in php

When performing data query, sometimes the query time is too long. At this time, the page will freeze and wait, bringing a bad experience to the user. In order to improve this situation, you can use some techniques to optimize the query, and at the same time let the user know that the query is in progress through prompt information.

1. Optimize query

1. Use index

When a large amount of data appears in the table in the database, query optimization through index can improve the query speed. An index is a data structure that speeds up query and sort operations. If indexes are not used, all data will be scanned to find the required information during actual queries, which will consume a lot of time and resources. Therefore, when designing the database, reasonable indexes should be set up to optimize queries.

2. Avoid using “＊”

When making queries, try to avoid using “＊” to obtain all data. This is because querying all data requires retrieving all columns in the table, which will cause the query to take too long. And if you only query the required columns, the query time can be greatly shortened.

3. Optimize query statements

Some query statements will cause the query time to be too long, such as using subqueries, joint table queries, etc. When encountering this kind of situation, you can try to optimize the query statement and reduce the query time. For example, for joint table queries, inner joins or outer joins can be used to optimize.

2. Prompt query status

When performing a long-term query, the page may appear "white screen" or stuck. At this time, the user will not be able to feel whether the query has started. , or the query has been completed. Therefore, query status should be displayed on the page to let the user know that the query is in progress.

1. Display the query progress bar

Display the query progress bar on the page to let the user know that the query is in progress. At the same time, the change of the progress bar allows users to perceive the progress of the query, thereby reducing the user's waiting time.

2. Use dynamic loading

If the query takes a long time, you can use dynamic loading to optimize it. Dynamic loading can submit a process when the query starts, and then return the results to the user when the query is completed. In this way, users can see and interact with the page content first, without waiting for the end of the query to operate.

3. Use asynchronous query

Asynchronous query can perform other operations while querying, without waiting for the query to be completed. For example, you can use Ajax to implement asynchronous queries and insert query results into the page without reloading the entire page.

3. Error handling

When querying, some errors may occur, such as database connection failure, SQL statement error, etc. At this time, the error should be handled and the corresponding information provided to the user. prompt information.

1. Display error message

When an error occurs in the query, the corresponding error message should be displayed to the user. For example, you can prompt on the page "Database connection failed, please try again later", or "Query statement error, please check and try again."

2. Provide solutions

In addition to displaying error messages, users should be provided with corresponding solutions. For example, if a query fails because of a network connection problem, you can prompt the user to check the network connection or try again later. If there is an error in the SQL statement, the user can be prompted to check the statement or contact the administrator for help.

Summary

When conducting long-term queries, by optimizing query statements, prompting query status and processing error messages, the user experience can be improved and user waiting time can be reduced. At the same time, we also need to start with the design and optimization of the database and speed up queries by setting up reasonable indexes.

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