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I'm running this SQL query:
SELECT wp_woocommerce_order_items.order_id As No_Commande FROM wp_woocommerce_order_items LEFT JOIN ( SELECT meta_value As Prenom FROM wp_postmeta WHERE meta_key = '_shipping_first_name' ) AS a ON wp_woocommerce_order_items.order_id = a.post_id WHERE wp_woocommerce_order_items.order_id =2198 And I get this error:
#1054 - Unknown column 'a.post_id' in 'on clause'.
I think my code is pretty simple, but I can't make it right. What am I doing wrong?
564
Rather than using the table names, you may also use table alias as specifying the tables in the LEFT OUTER JOIN query. LEFT JOIN sto_orders ORDs ON EMPs.id=ORDs. emp_id; The same result is retrieved as in case of the first example.
Move the 'Reserve' table named in the subquery to the FROM clause and join it to 'Customers' using LEFT JOIN. The WHERE clause compares the customer_id column to the ids returned from the subquery. Hence convert the IN expression to an explicit direct comparison between id columns of two tables in the FROM clause.
An SQL alias is useful for simplifying your queries and making the query and its result more readable. This article explains why and how you can use aliases in your SQL queries. You can temporarily rename a table or a column by giving it another name. This is known as an SQL alias.
A subquery can be used with JOIN operation. In the example below, the subquery actually returns a temporary table which is handled by database server in memory. The temporary table from the subquery is given an alias so that we can refer to it in the outer select statement.
You didn't select post_id in the subquery. You have to select it in the subquery like this:
SELECT wp_woocommerce_order_items.order_id As No_Commande FROM wp_woocommerce_order_items LEFT JOIN ( SELECT meta_value As Prenom, post_id -- <----- this FROM wp_postmeta WHERE meta_key = '_shipping_first_name' ) AS a ON wp_woocommerce_order_items.order_id = a.post_id WHERE wp_woocommerce_order_items.order_id =2198 I recognize that the answer works and has been accepted but there is a much cleaner way to write that query. Tested on mysql and postgres.
SELECT wpoi.order_id As No_Commande FROM wp_woocommerce_order_items AS wpoi LEFT JOIN wp_postmeta AS wpp ON wpoi.order_id = wpp.post_id AND wpp.meta_key = '_shipping_first_name' WHERE wpoi.order_id =2198 If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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