golang delete statement

Golang is a strongly typed compiled language with the advantages of efficiency, simplicity, and scalability, and has become one of the more popular programming languages ​​at present. In daily programming in Golang, we often encounter situations where data needs to be deleted. So how to write a delete statement in Golang? This article will give you a detailed introduction to how to write Golang's delete statement.

1. Basic concepts

In Golang, the delete operation corresponds to the DELETE statement in the database operation, and its function is to delete the specified data from the data table. Of course, when performing a delete operation, we need to first clarify the following concepts:

1. Data table: The delete operation targets the data in the data table, so the data table to be operated must first be determined.
2. WHERE clause: This clause is used to specify the data to be deleted. It is usually necessary to provide some search conditions to find the specified data for deletion.

2. Basic syntax of delete statement

In Golang, the basic syntax of delete operation is as follows:

DELETE FROM `table_name` WHERE `condition`;

Among them, DELETE is the keyword, which means to perform deletion Operation; FROM is followed by the name of the data table to be deleted; WHERE is followed by the deletion condition, which is used to specify the data to be deleted.

For example, if we want to delete all user data younger than 20 years old from a data table named users, we can write the following delete statement:

DELETE FROM users WHERE age < 20;

3. Execute the delete statement in Golang

In Golang, to perform a delete operation, you need to use the database/sql standard library and the corresponding database driver. Here we take Sqlite database as an example to introduce how to perform a delete operation.

1. Import necessary libraries

Before writing the Golang delete statement, you need to import some necessary libraries, as shown below:

import (
    "database/sql"
    "fmt"
    _ "github.com/mattn/go-sqlite3"
)

Among them, # The ##database/sql package is the standard library for relational database operations in Golang, and github.com/mattn/go-sqlite3 is the driver library for connecting to Sqlite databases.

Connect to the database

Before executing the delete statement, you need to connect to the database first. The code to connect to the database is as follows:

db, err := sql.Open("sqlite3", "./test.db")
if err != nil {
    fmt.Println(err)
    return
}
defer db.Close()

Here, a Sqlite database named test.db will be opened, and the connection information is stored in the db variable. Use the

defer statement to close the connection to ensure that the database connection can be closed normally when the program execution ends.

Writing a delete statement

Next, based on the above syntax example, write a SQL statement to delete data in the data table:

sqlStr := "DELETE FROM users WHERE age < ?"

Among them,

users is the name of the data table to be deleted, age < ? means to delete data whose age is less than the provided parameter value.

Perform deletion operation

The code to perform deletion operation is as follows:

stmt, err := db.Prepare(sqlStr)
if err != nil {
    fmt.Println(err)
    return
}
defer stmt.Close()

result, err := stmt.Exec(20)
if err != nil {
    fmt.Println(err)
    return
}

rowsAffected, err := result.RowsAffected()
if err != nil {
    fmt.Println(err)
    return
}

fmt.Printf("删除了%d条数据
", rowsAffected)

In the above code, use

db.Prepare()Function compiles SQL statements and creates an stmt object. Use the Exec method of the stmt object to execute the SQL statement, passing the parameters to the placeholders in the SQL WHERE clause. In addition, use the result.RowsAffected() method to get the number of rows affected by deletion and output it.

At this point, the introduction to how to write delete statements in Golang is completed.

Summary

This article mainly introduces how to write delete statements in Golang, including basic concepts, basic syntax, and specific steps to perform delete operations. I believe that after reading this article, everyone will have a deeper understanding of Golang's delete statements. Of course, in addition to Sqlite database, Golang also supports MySQL, PostgreSQL and other mainstream databases. You can choose according to your needs in actual development.

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