dongsaolian8786
dongsaolian8786
2017-09-06 21:10
浏览 85

如何使用golang sql在postgres中选择整个表格?

I'm fairly new to posgres and Go, but have been struggling for a while on this. I'm currently trying to send a query to retrieve everything from a table. When I try to use

SELECT * FROM land_registry_price_paid_uk

within postgres, it shows everything, but when I do the same using Query, I get.

sql: expected 16  destination arguments in Scan, not 1

This is the current code that I have.

fmt.Printf("user: %s, password: %s, dbName: %s", user, password, dbName)
connectionString := fmt.Sprintf("user=%s password=%s dbname=%s sslmode=%s", user, password, dbName, "disable")
var err error
a.DB, err = sql.Open("postgres", connectionString)
if err != nil {
    log.Fatal(err)
}
rows, err := a.DB.Query("SELECT ( * ) FROM land_registry_price_paid_uk")
if err != nil {
    log.Fatal(err)
}
defer rows.Close()
println(rows)
for rows.Next() {
    var name string
    if err := rows.Scan(&name); err != nil {
        log.Fatal(err)
    }
    fmt.Printf("this is something: %s
", name)

Any help is appreciated.

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2条回答 默认 最新

  • duannai5879
    duannai5879 2017-09-06 21:25
    已采纳

    Looks like your query is working just fine, you are returning 16 columns of data and trying to scan them all into a single string variable, you will need to provide a holder variable for each column:

    var name string
    // vars to hold other column values go here
    
    // then reference vars in table order as args to row.Scan below
    if err := rows.Scan(&name); err != nil {
        log.Fatal(err)
    }
    

    if you have not used sql/go before you may also want to look into the special types provided for coping with nullable values as you will likely need these as well:

    NullString example

    Update:

    To further illustrate, say you had a three column table which consisted of the following fields:

    • id (int)
    • name (string)
    • optional_data (string, nullable)

    You might read the row as follows (not tested):

    var (
        id int 
        name string
        optionalData sql.NullString
    )
    
    if err := rows.Scan(&id, &name, &optionalData); err != nil {
        log.Fatal(err)
    }
    
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  • dtlygweb2017
    dtlygweb2017 2019-06-30 05:59

    Thanks a lot it was useful for me. but I would like to add a little bit more of information. well I don't know what is your goalng's version but I'm using version 1.11.2 on windows/386 but when I added the parentheses this not worked. but without them it run perfect.

    use this: rows, err := a.DB.Query("SELECT * FROM mytable") instead of : rows, err := a.DB.Query("SELECT ( * ) FROM mytable")

    and here is my example:

    rows, err := db.Query("SELECT * FROM words")
        if err != nil {
            log.Fatal(err)
        }
        defer rows.Close()
        println(rows)
        for rows.Next() {
            var word, exa1, exa2, mean string
            var id int
            if err := rows.Scan(&id, &word, &exa1, &exa2, &mean); err != nil {
                log.Fatal(err)
            }
            fmt.Printf("id: %d
     word: %s 
     example1: %s 
     example2: %s 
     meaning: %s
    ---
    
    ", id, word, exa1, exa2, mean)
        } 
    
      I hope this will be useful.
    
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