doujiang7258 2019-03-04 16:30
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MySQL和MariaDB SELECT返回类型的区别

When executing a SELECT query, and storing the results in a struct with a field of type interface, the resulting type differs between int64 and []uint8 depending if the db I am using is a MySQL database, or MariaDB.

This is related to a previous question that I had asked (and was answered) : Go SQL query inconsistency

Given an interface as follows:

type Result struct {
    Afield string      `db:"A"`
    Bfield interface{} `db:"B"`
    Cfield string      `db:"C"`
    Dfield string      `db:"D"`
}

And database table:

A : VARCHAR(50)
B : INT
C : VARCHAR(50)
D : VARCHAR(50)

The query I would like to execute:

SELECT A, B, C, D FROM table WHERE A="a"

How it is being executed:

db.Get(&result, `SELECT A, B, C, D FROM table WHERE A=?`, "a")

The issue

If being executed on a MySQL database, the type of Bfield is int64 (desired), However if being executed on MariaDB, the type is instead []uint8.

Why is the type of Bfield different, depening on if the query is executed on a MySQL db or MariaDB?

Potentially useful info:

db is of type: *sqlx.DB, then passed to function that executes the query, where db is type Connection.

// Connection is an interface for making queries.
type Connection interface {
    Exec(query string, args ...interface{}) (sql.Result, error)
    Get(dest interface{}, query string, args ...interface{}) error
    Select(dest interface{}, query string, args ...interface{}) error
}

I am using https://github.com/jmoiron/sqlx

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