Check if database table exists using golang

Question

I am trying to do a simple thing, check if there is a table, if not then create that table in database.

Here this is the logic I used.

    test := "June_2019"
    sql_query := `select * from ` + test + `;`

    read_err := db.QueryRow(sql_query, 5)
    error_returned := read_err.Scan(read_err)
    defer db.Close()

    if error_returned == nil {
        fmt.Println("table is there")

    } else {
        fmt.Println("table not there")
    }

In my database I have June_2019 table. But still this code returns me not nil value. I used db.QueryRow(sql_query, 5) 5 as I have five colomns in my table.

What am I missing here? I am still learning golang.

Thanks in advance.

Offtopic; Consider if making a table from application code is logical as your MySQL user has to be more powerfull have CREATE and maybe DROP rights, which can be unsafe.. Also seeing metadata (Year) used as table separator, why are you doing this? ideally you should have one table where you have a year column — Raymond Nijland
– Raymond Nijland, Commented Jul 6, 2019 at 14:42
.. As MySQL can handle milllion or even in the billions numbers of records just fine in one table when indexes are involved and when in doubt deploy Partitioning which does more or less the same thing you are doing but better in every way.. — Raymond Nijland
– Raymond Nijland, Commented Jul 6, 2019 at 14:44
@RaymondNijland true. but here I did this to learn golang and satisfy a simple need. — Sachith Muhandiram
– Sachith Muhandiram, Commented Jul 6, 2019 at 15:02
SQL is a language. go is a language. When trying to solve a problem, it's best to use the language best suited for the task at hand. Checking for table existence should be left to the SQL side of things e.g. CREATE TABLE IF NOT EXISTS — colm.anseo
– colm.anseo, Commented Jul 6, 2019 at 15:37

Sachith Muhandiram · Accepted Answer · 2019-07-07 03:04:50Z

3

I have solved the problem using golang and MySQL.

_, table_check := db.Query("select * from " + table + ";")

    if table_check == nil {
        fmt.Println("table is there")
    } else {
        fmt.Println("table not there")
    }

I have used db.Query() which returns values and and error, here I checked only error.

I think most people thought I want to do it in MySQL way, I just wanted to learn how to use golang to do MySQL operations.

answered Jul 7, 2019 at 3:04

Sachith Muhandiram

2,97811 gold badges54 silver badges113 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

k3a Over a year ago

You forgot rows.Close() (the first return variable) in case of table_check == nil and that will probably leak memory

financial_physician Over a year ago

@k3a does that mean that you shouldn't assign the result to _ so that you can close the object?

k3a Over a year ago

Yes, every Query() call with nil error returns *sql.Rows. Those rows need a full for loop iteration with Next() until Next() returns false (which would call Close() internally) or an explicit call to Close() to free the memory used by the resultset. Close() is idempotent and can also be called multiple times safely.

Collectives™ on Stack Overflow

Check if database table exists using golang

1 Answer 1

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related