Description:
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with mysqli_multi_query I can execute several SQL commands at once;

if an error happens in the second or third or ... SQL command, mysqli_multi_query returns TRUE, mysqli_error etc. contain no data on the error

thus, it is impossible to detect and/or analyse errors in multi query statements

Reproduce code:
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$ok = mysqli->multi_query("SELECT 1; SELECT blabla");

Expected result:
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$ok should be FALSE, $mysqli->error should specify error

(actually, $mysqli->error is inadequate; something like $mysqli->multi_error would be better, returning an array with the error messages for all statements)

Actual result:
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$ok is TRUE