What is GROUP BY and ORDER BY in DB2?
DB2 Order by clause is used to sort the result table values by the sort Key order. Here, sort key can be the column name or column number. Results can be sorted either by Ascending (ASC) or by Descending (DESC) order.
What is the use of GROUP BY statement in DB2?
The GROUP BY clause allows you to find the characteristics of groups of rows rather than individual rows. When you specify a GROUP BY clause, SQL divides the selected rows into groups such that the rows of each group have matching values in one or more columns or expressions.
What is true for GROUP BY ORDER BY clause?
Answer: A. Processing order starts from FROM clause to get the table names, then restricting rows using WHERE clause, grouping them using GROUP BY clause, restricting groups using HAVING clause. ORDER BY clause is the last one to be processed to sort the final data set.
How do I join two tables in DB2?
- Inner join. You can use an inner join in a SELECT statement to retrieve only the rows that satisfy the join conditions on every specified table.
- Left outer join. The LEFT OUTER JOIN clause lists rows from the left table even if there are no matching rows on right table.
- Right outer join.
- Full outer join.
What is cursor in Db2?
Db2 has a mechanism called a cursor . In Db2, an application program uses a cursor to point to one or more rows in a set of rows that are retrieved from a table. You can also use a cursor to retrieve rows from a result set that is returned by a stored procedure.
Does the group by column have to be in the select clause?
GROUP BY odate, partno; If you specify the GROUP BY clause, columns referenced must be all the columns in the SELECT clause that do not contain an aggregate function. These columns can either be the column, an expression, or the ordinal number in the column list.
Can we use GROUP BY and having clause together?
HAVING Clause always utilized in combination with GROUP BY Clause. HAVING Clause restricts the data on the group records rather than individual records. WHERE and HAVING can be used in a single query.
Can I use GROUP BY and ORDER BY together?
Both GROUP BY and ORDER BY are clauses (or statements) that serve similar functions; that is to sort query results. However, each of these serve very different purposes; so different in fact, that they can be employed separately or together.
What is inner join and outer join in DB2?
The JOIN is used to combine data from one or more tables in DB2. There are two main types of JOIN — INNER JOIN and OUTER JOIN. The basic difference between them is, INNER JOIN is an intersection of two or more tables while outer join is union of two or more tables. For example, consider the table below.
How does Db2 cursor work?
DB2 uses a cursor to make the rows, from the results table, available to the application program. A cursor identifies the current row of the results table. When you use a cursor, the program can retrieve each row sequentially from the results table until end-of-data (i.e the not found condition SQLCODE=100).
What does the Db2 precompiler do?
The Db2 precompiler scans a program and copies all of the SQL statements and host variable information into a DBRM (database request module). The precompiler also returns source code that has been modified so that the SQL statements do not cause errors when you compile the program.
When to use ORDER BY clause in DB2?
ORDER BY. DB2 Order by clause is used to sort the result table values by the sort Key order. Here, sort key can be the column name or column number. Results can be sorted either by Ascending (ASC) or by Descending (DESC) order. ASC is the default order by clause. If you do not specify any collating sequence in order by clause it sorts
When to use order by and group by in SQL?
It is used to arrange similar data into group. The GROUP BY clause follows the WHERE clause and comes before the ORDER BY clause. SELECT column1, column 2… FROM table_name WHERE [condition] GROUP BY column1, column2 ORDER BY column1, column2;
When to use ASC or order by in DB2?
If you skip it, Db2 will use ASC by default. When evaluating the SELECT statement with an ORDER BY clause, Db2 evaluates the clauses in the following order: FROM, SELECT, and ORDER BY. In other words, Db2 always evaluates the ORDER BY clause at last.
How to sort result set in ascending order in DB2?
First, specify expression1, expression2, etc., that can be columns or expressions by which you want to sort the result set. Second, use ASC to sort the result set in ascending order (from low to high) and DESC to sort the result set in descending order (from high to low).
