Syntax error with SQL in PHP - php

Question

I'm trying to set the column of a table to a string in every row if the column exists. However, I am receiving SQL syntax errors and can't pinpoint what exactly the issue is:
while($db = mysqli_fetch_array(mysqli_query($conn, "SHOW DATABASES"))){
$id = $db['id'];
$sql = /** #lang text */
"SELECT IF( EXISTS(
SELECT DISTINCT `info`
FROM INFORMATION_SCHEMA.COLUMNS
WHERE COLUMN_NAME IN ('borrower')
AND TABLE_SCHEMA = '$db'))
BEGIN
UPDATE `info`
SET `borrower` = '****'
WHERE `id` = '$id'
END";
$query = mysqli_query($conn, $sql);
if (!$query){
// Deal with error
}
}
The syntax error I receive back:
information_schemadb1You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')BEGINUPDATE infoSET borrower = '****'' at line 5
I know it must be something very small but I have been stuck for a while and can't seem to find my error.

Answer 1

Try this syntax for the query-
IF EXISTS (SELECT DISTINCT `info`
FROM INFORMATION_SCHEMA.COLUMNS
WHERE COLUMN_NAME IN ('borrower')
AND TABLE_SCHEMA = '$db')) THEN
UPDATE `info`
SET `borrower` = '****'
WHERE `id` = '$id'
END IF;
I added Then in the end of the if condition and End if instead of only if, and I removed the select to. What are you trying to select? it is only update clause.
update
Example from here
you can't use it like a normal query. Control structures like IF or
WHILE are only allowed in stored procedures or functions.
MYSQL panel
delimiter $$
create procedure YourIfConditionSP()
begin
IF EXISTS (SELECT DISTINCT `info`
FROM INFORMATION_SCHEMA.COLUMNS
WHERE COLUMN_NAME IN ('borrower')
AND TABLE_SCHEMA = '$db') THEN
UPDATE `info`
SET `borrower` = '****'
WHERE `id` = '$id';
END IF;
end $$
delimiter ;
And you have to change your php code for calling the stored procedure.
PHP
//run the stored procedure
$result = mysqli_query($connection,
"CALL YourIfConditionSP") or die("Query fail: " . mysqli_error());
How to call a MySQL stored procedure from within PHP code?