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--- database:mysql [2023/11/02 10:56] – [Mysql basic commands] skipidar
+++ database:mysql [2023/11/02 11:04] (current) – skipidar
@@ Line 517: / Line 517: @@
 == IFNULL(), ISNULL(), COALESCE(), and NVL() Functions ==
-| ''IFNULL(COLUMN, DEFAULTVALUE) -> COLUMN or DEFAULT'' | The IFNULL() function returns a specified value if the expression is NULL. |
+| ''IFNULL(COLUMN, DEFAULTVALUE) -> COLUMN_VALUE or DEFAULT'' | The IFNULL() function returns a specified value if the expression is NULL. |
+| ''ISNULL(COLUMN, DEFAULTVALUE) -> BOOL'' | Return boolean. |
 | ''COALESCE(val1, val2, ...., val_n)'' | Return the first non-null value in a list:  |
@@ Line 525: / Line 526: @@
 SELECT ProductName, UnitPrice * (UnitsInStock + IFNULL(UnitsOnOrder, 0))
 FROM Products;
+--- using boolean ISNULL
+SELECT OrderID,
+CASE
+    WHEN ISNULL(AmountDue) THEN "Paid in full"
+    WHEN DATE(DueDate) < date(NOW()) THEN "Order is past due"
+    ELSE CONCAT("Order is due on ", CONVERT(VARCHAR, DueDate, 121))
+END
+FROM OrderDetails;
 </sxh>
+== Stored Procedure Example ==
+<sxh sql>
+--- procedure
+CREATE PROCEDURE SelectAllCustomers
+AS
+SELECT * FROM Customers
+GO;
+--- execute
+EXEC SelectAllCustomers;
+--- procedure with args
+CREATE PROCEDURE SelectAllCustomers @City nvarchar(30)
+AS
+SELECT * FROM Customers WHERE City = @City
+GO;
+--- exec
+EXEC SelectAllCustomers @City = 'London';
+</sxh>