You must ensure that the label in the END LOOP statement matches the label at the beginning of the same loop statement (the compiler does not check).įor information about the cursor FOR LOOP, see "Query Result Set Processing With Cursor FOR LOOP Statements". Labels are recommended for nested loops to improve readability. if table pageviews is partitioned on column date, SQL Server. LOOP statements can be labeled, and LOOP statements can be nested. Database developers can partition a SQL Server database table according to months. For information about exceptions, see "Overview of Exception Handling".) Oracle recommends using these statements instead of the "GOTO Statement", which can exit a loop or the current iteration of a loop by transferring control to a statement outside the loop. The statements that exit the current iteration of a loop are:ĮXIT, EXIT WHEN, CONTINUE, and CONTINUE WHEN and can appear anywhere inside a loop, but not outside a loop. You can use the CASE statement within a SQL statement. Loop statements run the same statements with a series of different values. Case Statement The CASE statement has the functionality of an IF-THEN-ELSE statement. For this purpose, a simple CASE statement is clearer-see Example 4-6. Logically equivalent nested IF THEN ELSE statementsĮxample 4-5 uses an IF THEN ELSIF statement with many ELSIF clauses to compare a single value to many possible values. The SQL language is subdivided into several language elements, including: Clauses, which are constituent components of statements and queries. The third if checks if the value of the variable is orders then fetch the records from the orders table.įinally, the ELSE statement for any other value of the variable should get the records of employee’s salary paid table.'Sales = ' || sales || ', bonus = ' || bonus || '.'Ī single IF THEN ELSIF statement is easier to understand than a logically equivalent nested IF THEN ELSE statement: - IF THEN ELSIF statement If the value is employees then get the sto_employees records. if the value is products then retrieve the data from sto_products table. So, the scenario is to check the value of a variable (table_name). Just for showing that you may nest to many levels, I am gone further by using another nested IF statement. Going another level in NESTED IF statement Try different values for the variable by your own table names and replace in the SELECT statement as well for experiencing it yourself. This tutorial shows you how to use the Oracle CASE expression including simple and searched CASE expression to add if-else logic to the SQL statements. There, we placed another condition to check. This is terminated by using the END keyword. You can see, inside the ELSE statement, the BEGIN keyword is used where another IF statement is placed (the nested IF).
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