Can Go's Rows.Scan ignore fields from SQL query

Question

The Rows.Scan method takes as many parameters as there are columns in the SQL query.

As the query being executed is SHOW COLUMNS FROM my_table I cannot omit any column which I don't require (or can I?).

Is there any way to ignore some fields from the query result set which is not required?

Below is my code:

rows, err := db.Query("SHOW COLUMNS FROM " + r.Name)
DieIf(err)
//var field, dataType, ignoreMe1, ignoreMe2, ignoreMe3 string
var field, dataType string
for rows.Next() {
                    //This Place
                    //   |
                    //   V
    if err := rows.Scan(&field, &dataType); err != nil {
        DieIf(err)
    }
    r.Attributes[field] = Attribute{
        Name:       field,
        DataType:   dataType,
        Constraint: false,
    }
}

error: sql: expected 5 destination arguments in Scan, not 2

Answer 1

So here I'm with one solution for you, try this one to get field and type from query.

package main

import (
    "fmt"
    _ "github.com/lib/pq"
    "database/sql"
)

func main() {

    db, _ := sql.Open(
        "postgres",
        "user=postgres dbname=demo password=123456")

    rows, _ := db.Query("SELECT * FROM tableName;")

    columns, _ := rows.Columns()
    count := len(columns)
    values := make([]interface{}, count)
    valuePtr := make([]interface{}, count)

    for rows.Next() {

        for i, _ := range columns {
            valuePtr[i] = &values[i]
        }

        rows.Scan(valuePtr...)

        for i, col := range columns {

            var v interface{}

            val := values[i]

            b, ok := val.([]byte)

            if (ok) {
                v = string(b)
            } else {
                v = val
            }

            fmt.Println(col, v)
        }
    }
}