How to write navicat query statement

Navicat query statements use standard SQL syntax, including SELECT, FROM, WHERE, ORDER BY and LIMIT. Example queries include retrieving all customer information, customer information that meets a condition (such as starting with "John"), and more complex data retrieval using functions (such as COUNT(), SUM()) and subqueries.

Navicat query statement writing guide

1. Syntax structure

Navicat query statement follows standard SQL syntax and contains the following parts:

• SELECT: Specifies the columns to be retrieved
• FROM : Specify the table to be queried
• WHERE: Specify the query conditions (optional)
• ORDER BY: Specify the sort order of the results (optional) )
• LIMIT: Limit the number of results returned (optional)

2. Query example

Get All customer information in table customers:

SELECT * FROM customers;

Get customer information that meets the conditions, the condition is: the customer name starts with "John":

SELECT * FROM customers WHERE name LIKE "John%";

Get the customers that meet the conditions Information, the condition is: the customer's age is greater than 30 years old, and sorted by age in ascending order:

SELECT * FROM customers WHERE age > 30 ORDER BY age ASC;

Get customer information that meets the conditions, the condition is: the customer's name starts with "Mary", and limits the first 5 records returned ：

SELECT * FROM customers WHERE name LIKE "Mary%" LIMIT 5;

3. Commonly used functions

In addition to basic query operations, Navicat also supports a variety of commonly used functions, such as:

• COUNT(): Calculate the number of rows
• SUM(): Calculate the sum
• AVG(): Calculate the average
• MAX(): Get the maximum value
• MIN(): Get the minimum value

4. Subquery

Navicat allows the use of subqueries in queries, that is, nesting a query in the main query. This can be used to perform more complex data retrieval operations.

The above is the detailed content of How to write navicat query statement. For more information, please follow other related articles on the PHP Chinese website!