Replace Default Null Values Returned from Left Outer Join

Replace Default Null Values Returned From Left Outer Join

That's as easy as

IsNull(FieldName, 0)

Or more completely:

SELECT iar.Description, 
ISNULL(iai.Quantity,0) as Quantity,
ISNULL(iai.Quantity * rpl.RegularPrice,0) as 'Retail',
iar.Compliance
FROM InventoryAdjustmentReason iar
LEFT OUTER JOIN InventoryAdjustmentItem iai on (iar.Id = iai.InventoryAdjustmentReasonId)
LEFT OUTER JOIN Item i on (i.Id = iai.ItemId)
LEFT OUTER JOIN ReportPriceLookup rpl on (rpl.SkuNumber = i.SkuNo)
WHERE iar.StoreUse = 'yes'

Replace returned null values in LEFT OUTER JOIN

In oracle and sql server, you can use the COALESCE (oracle version) function

SELECT ...., COALESCE(WO_BreakerRail.Date, @date)

Create a default value when left join returns null

You can use ISNULL() in select query.

eg; I have set as 0 when MerchantId is null and set empty string when MidName is null

ISNULL(MerchantId, 0)
ISNULL(MidName, '')

Do this in the main query.

eg;

select ISNULL(m.MerchantId, 0), ISNULL(Mid.MidName, '') 
from Users u

Left Join Overrides Non-Null Value with Null value when record is empty on second table

What you describe does work.

Demo:

mysql> create table qtrade (tid int);
Query OK, 0 rows affected (0.01 sec)

mysql> create table qsale (tid int);
Query OK, 0 rows affected (0.01 sec)

mysql> insert into qtrade set tid=42;
Query OK, 1 row affected (0.01 sec)

mysql> SELECT *
-> FROM `qtrade`
-> LEFT JOIN `qsale` ON qtrade.tid = qsale.tid;
+------+------+
| tid | tid |
+------+------+
| 42 | NULL |
+------+------+
1 row in set (0.00 sec)

mysql> SELECT *, COALESCE(qsale.tid, qtrade.tid) AS tid
FROM `qtrade` LEFT JOIN `qsale` ON qtrade.tid = qsale.tid;
+------+------+------+
| tid | tid | tid |
+------+------+------+
| 42 | NULL | 42 |
+------+------+------+
1 row in set (0.00 sec)

MySQL query result sets allow multiple columns to have the same name.

But the problem arises when you have a client that fetches the results into an associative array or hashmap, which only allows one entry per name.

In that case, the only alternative is to change the client code to fetch results into an ordinal array instead of an associative array, and then reference the columns of the result by position instead of by name.

I never use SELECT * in production code anyway. Just write out the columns. If typing 32 column names is the bottleneck in your programming productivity, then you're doing it wrong.

Replace Left Outer Join Null values with a string

Since you need a varchar value in the same field together with int/bool, you need to make sure every row of that field has the same data type.

Isnull(Convert(varchar(50), ReturnedValue), 'UnRegistered') AS ReturnedValue

Or you can use a CASE as

Case when ReturnedValue is null then 'UnRegistered'
else convert(varchar(50), ReturnedValue) end as ReturnedValue


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