How to fix "ambiguous" where clause in procedure - mysql

Question

I am getting an error:
1052 - Column 'orderId' in where clause is ambiguous
when trying to do CALL GetOrderById(2000)
BEGIN
SELECT
hsorders.*,
hslineitem.partNum, hslineitem.price
FROM
hsorders
JOIN hslineitem ON hslineitem.orderId = hsorders.orderId
WHERE
orderId = orderId;
END
I need to pass an Id and join data from two tables that have the same `orderId``.
What am I doing wrong?

Answer 1

You are getting the error because orderid is in both tables. Hence, the SQL engine does not know which orderid the where clause refers to.
Let me hypothesize that you have a parameter or variable called orderid.
That name conflicts with columns of the same name in the table. That is why I use prefixes. For instance, if orderid is being passed in as a parameter, I would name it in_orderid. If it were a local variable, I might use v_orderid.
Then the code would look like this:
BEGIN
SELECT o.*, li.partNum, li.price
FROM hsorders o JOIN
hslineitem li
ON li.orderId = o.orderId
WHERE o.orderId = v_orderId;
END;
Notice that I also added table aliases so the query is easier to write and to read.

Answer 2

You need to use alias:
BEGIN
SELECT
hsorders.*,
hslineitem.partNum, hslineitem.price
FROM hsorders
JOIN hslineitem ON hslineitem.orderId = hsorders.orderId
WHERE
hsorders.orderId = p_orderId; -- I suggest to rename parameter to avoid
-- name collision
END

Answer 3

ambiguous means use table name or alias name before FIELD
Like hsorders.orderId in where clause.

Answer 4

Use alias while joining tables. It will be helpful to distinguish the columns if they are in both the tables.
When to use alias
BEGIN
SELECT
HO.*,
HL.partNum, HL.price
FROM
hsorders HO
JOIN hslineitem HL
ON HO.orderId = HL.orderId
END
you have already used ON clause to give HO.orderId = HL.orderId
so you do not have to use where clause again