go sql scan
What is Go SQL Scan?
Go SQL Scan is a feature in Go programming language that allows developers to scan database rows from a SQL query result into a struct or a slice of structs.
How does it work?
The basic idea behind Go SQL Scan is to take the results of a SQL query and automatically map them to a Go struct or a slice of structs. In order to do this, the Go compiler needs to be able to match the columns of the SQL result with the fields of the struct. This can be done either by ordering the columns in the SELECT statement to match the order of struct fields, or by using aliases to explicitly map column names to struct field names.
Why use Go SQL Scan?
Go SQL Scan provides a simple and intuitive way to retrieve data from SQL databases and map it to a Go struct or slice. This can save a lot of time and effort compared to manually parsing the results of SQL queries. Additionally, Go SQL Scan provides type safety and helps prevent runtime errors caused by mismatched types.
Example Usage
Here is an example of how Go SQL Scan can be used to retrieve data from a SQLite database and map it to a struct:
```type record struct { id int name string}func main() { db, err := sql.Open("sqlite3", "test.db") if err != nil { log.Fatal(err) } defer db.Close() rows, err := db.Query("SELECT id, name FROM mytable") if err != nil { log.Fatal(err) } defer rows.Close() var result []record for rows.Next() { var r record err = rows.Scan(&r.id, &r.name) if err != nil { log.Fatal(err) } result = append(result, r) } err = rows.Err() if err != nil { log.Fatal(err) } fmt.Println(result)}```In this example, we define a simple struct called 'record' with two fields: 'id' and 'name'. We then open a connection to a SQLite database and query the 'mytable' table, selecting only the 'id' and 'name' columns. We loop through the result rows and decode each row into a new 'record' struct by calling rows.Scan() with the addresses of the struct fields as arguments. Finally, we print the resulting slice of 'record' structs.
Conclusion
Go SQL Scan is a powerful and convenient feature of the Go programming language that makes it easy to retrieve data from SQL databases and map it to Go structs or slices. It provides a simple and intuitive way to read data from databases, and helps prevent runtime errors and type mismatches. By using Go SQL Scan, developers can save time and effort when working with SQL databases, and focus on building great applications instead.
