QSqlQuery does not prepare sql for PostgreSQL

Question

I'm trying to prepare sql query with QSqlQuery, but for every sql i'm getting an error about EXECUTE syntax.

Here I'm connecting to database:

QSqlDatabase db = QSqlDatabase::addDatabase("QPSQL");
db.setHostName("localhost");
db.setDatabaseName("test_db");
db.setUserName("postgres");

if (!db.open())
{
    qWarning() << "DB not opened";
    return;
}

And here preparing sql:

QString str { "INSERT INTO :table (test_text, test_int) VALUES (:txt, :int)" };

QSqlQuery query(db);
query.prepare(str);
query.bindValue(":table", "test_table");
query.bindValue(":txt", "test");
query.bindValue(":int", 1);

Then I execute prepared query

if (!query.exec())
{
    qWarning() << query.lastError();
} else {
    qWarning() << "success!";
}

And an error occurs:

QSqlError("42601", "QPSQL: Unable to create query", "ERROR: syntax error at or near: \"(\")\nLine 1: EXECUTE ('test_table', NULL, NULL)\n ^\n(42601)"

But next code works:

query.exec(QStringLiteral("INSERT INTO %1 (test_text, test_int) VALUES (%2, %3)").arg("test_table").arg("'test'").arg(1))

I used to work with MySQL and it works perfectly.

chehrlic · Accepted Answer · 2020-03-11 06:14:16Z

2

You can't use a placeholder for the table name. Also you should check for the return value of QSqlQuery::prepare()

answered Mar 11, 2020 at 6:14

chehrlic

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