Where clause applied to only one column in join
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I'm having some trouble with writing a certain SQL query. I have a wallet and a balance which I do join. The query now looks like that:
SELECT `balances`.`id` AS `id`, FROM `wallet` LEFT JOIN `balances` ON ( `wallet`.`currency` = `balances`.`currency` ) WHERE `balances`.`user_id` = '181'
Because of the
where clause, the query returns just matching records. I want to get all records from wallets table and only those from balances which do match where clause... hope I explained it well enough!
SELECT w.*,t.* FROM wallet w LEFT JOIN ( select * from balances where user_id = 181 ) t ON w.currency =t.currency
SQL Joins Using WHERE or ON, Normally, filtering is processed in the WHERE clause It's possible, though that you might want to filter one or both of the tables before joining them You can think of it as a WHERE clause that only applies to one of the tables. displayed in the column that pulls from the other table: When we add a where clause with a left outer join, it behaves like an inner join, where the filter is applied after the ON clause, showing only those rows having fruit with the name “apple.” Query 1.3 – A Left Outer Join with the ON Clause
Issue is you are applying filter on left join table wallets.
use below query.
SELECT `balances`.`id` AS `id`, FROM `wallet` LEFT JOIN (select * from `balances` `user_id` = '181') ON ( `wallet`.`currency` = `balances`.`currency` );
SQL joins and how to use them, In most cases this join condition is created using the primary key of one table and is a definite match between the values in the two columns used in the condition . Where the join condition is met, the rows of the two tables are joined, just as� The condition in the WHERE clause is applied so that the statement only retrieves the data from the US, UK, and China rows. Because we use the LEFT JOIN clause, all rows that satisfy the condition in the WHERE clause of the countries table are included in the result set.
The question is not fully clear, but you almost definitely need an extra
join clause on some sort of ID. Now there is no way to match a wallet with its balance(s). Assuming that balance have eg. a
wallet_id, you'll want something like:
SELECT `balances`.`id` AS `id`, FROM `wallet` LEFT JOIN `balances` ON (`wallet`.`id` = `balance`.`wallet_id` ) WHERE `balances`.`user_id` = '181'
SQL Inner Join to Two or More Tables, Use it to combine columns from two or more tables via a join condition. In this example we used the letter P. It could really be any number of characters, but I� You cannot specify the (+) operator in a query block that also contains FROM clause join syntax. The (+) operator can appear only in the WHERE clause or, in the context of left-correlation (when specifying the TABLE clause) in the FROM clause, and can be applied only to a column of a table or view.
SQL Server LEFT JOIN By Practical Examples, This tutorial introduces you to the SQL Server LEFT JOIN clause and shows you how to use it to If no matching rows found in the right table, NULL are used. SELECT select_list FROM T1 LEFT JOIN T2 ON join_predicate; If a pair of rows causes the join predicate to evaluate to TRUE , the column values from these� Where Clause applied first and then Having Clause. WHERE Clause restricts records before GROUP BY Clause, whereas HAVING Clause restricts groups after GROUP BY Clause are performed. WHERE Clause can be utilized with SELECT, UPDATE, DELETE, and INSERT, whereas HAVING can be utilized only with SELECT statement. Image Source. GROUP BY With JOIN
Documentation: 9.2: Table Expressions, However, the reference produces only the columns that appear in the named table Parentheses can be used around JOIN clauses to control the join order. The ON clause is the most general kind of join condition: it takes a Boolean value� The FROM clause in every SQL command tells the engine from where to read the rows. The data is stored on the disk and is fetched into the memory for processing. As the rows are read one by one from the disk to the memory, they are checked for the WHERE clause. The rows that fail the WHERE clause aren’t loaded into the memory.
WHERE Clause, WHERE Clause Purpose Filters rows that satisfy a conditional expression in a correlated subquery inside a HAVING clause, and the aggregate is applied on outer Defining join indexes on a NoPI or column‑partitioned table can slow down� NATURAL PREDICTION JOIN automatically maps together column names from the source query that match column names in the model. If you use NATURAL PREDICTION, you can omit the ON clause. The WHERE condition can be applied only to predictable columns or related columns.
PostgreSQL INNER JOIN, Suppose that you have two tables A and B. The table A has a column pka whose value (table B ) in the INNER JOIN clause and provide a join condition after the ON keyword. To join more than three tables, you apply the same technique. If the WHERE clause contains a condition that compares a column from table B with a constant, then the (+) operator must be applied to the column so that Oracle returns the rows from table A for which it has generated nulls for this column. Otherwise Oracle will return only the results of a simple join. In a query that performs outer joins of
- Can you clarify what you want the end result to look like? At first glance it looks like this should be two separate queries.
- Can you provide an example, clarifying what is the actual result and what do you expect instead?
- you can use the SQL UNION Operator
- Let's say there is like 100 wallet kinds, one wallet = one balance, certain user X have 5 balances so... I want querry to return all those 100 wallets and matching balances from the balances table, but due to where clause querry returns just those 5 matching records...