Db2 WHERE clause: Filtering Rows Returned By a Query.
Summary: in this tutorial, you will learn how to query data from one or more column of a table by using the Db2 SELECT statement. Introduction to Db2 SELECT statement. The SELECT statement queries data from one or more tables in a database. It is one of the most complex SQL statements in Db2. In this tutorial, we will focus on using the SELECT statement to query data from a single table.
One of the things that confuse SQL users all the time is how DISTINCT and ORDER BY are related in a SQL query. The Basics. Running some queries against the Sakila database, most people quickly.
This is a valid alternative to using the DISTINCT keyword. If you need a refresher on the GROUP BY clause, then check out this question: Group By and Having. This question would probably be asked just to see how good you are with coming up with alternative options for SQL queries. Although, it probably doesn’t prove much about your SQL skills.
Write a query that returns the unique values in the year column, in chronological order. Try it out See the answer. DISTINCT can be particularly helpful when exploring a new data set. In many real-world scenarios, you will generally end up writing several preliminary queries in order to figure out the best approach to answering your initial question. Looking at the unique values on each column.
Learn how to use SQL SELECT DISTINCT statement with this tutorial. Select unique data from the columns of a table using the SQL SELECT DISTINCT statement. You just need to specify the column name which contains many same data and you want to fetch only the unique data. A table may contain many duplicate data and to get an accurate result on your application.
How to Limit Query Results for DB2 Databases. Many times users are only interested in a subset of the results returned from an SQL query. All versions of DB2 provide a mechanism for limiting the records returned from an SQL query with the FETCH FIRST clause. Newer versions of DB2 also support the LIMIT and LIMIT OFFSET clauses. Using the FETCH FIRST syntax or LIMIT syntax (for newer DB2.
The SQL DISTINCT keyword is used in conjunction with the SELECT statement to eliminate all the duplicate records and fetching only unique records. There may be a situation when you have multiple duplicate records in a table. While fetching such records, it makes more sense to fetch only those unique records instead of fetching duplicate records.