The SQL queries often need to access multiple relations from the data set in order to get the required result. This was a query imposed on a single relation now let’s move ahead and discuss queries requested on multiple relations. Along with these, we can include expressions where we can use comparison operators to compare operands in the expression. In where clause we can make use of logical connectives and, or & not. Like if we want the result relation to display names of instructors that have salaries greater than 50000. To get specific tuples in the result relation we can use the where clause to specify the particular condition. Then the SQL query you will impose on the data set is: In case, you want the result relation to display instructor name along with their salary which reduced by 10%. To eliminate the duplicates you can make use of the distinct keyword.įurther, you can even include the arithmetic expression in the select clause using operators such as +, -, *, and /. Now, if we have asked only for the dept_name in the above query by default it would have listed names of all the departments retaining the duplicates. So there is no need of imposing any condition. This query would display all the fields for all the records.Observe that here we have not included where clause in the query above as we want the name of all the instructors with their department name. The asterisks (*) is a special wild card that allows you to display all the fields. This will display all the first names and hire dates for all the records in the “TeamMembers” table. SELECT “FirstName”, “DateOfHire” FROM “TeamMembers” This is handy, because often you don’t need all the information the table. The dataset only contains the information you request. The results we get from a query is called a dataset.

The SELECT command lists a set of fields you want to extract FROM a certain table. SELECT field1, field2.fieldx FROM tablename The most basic form of the SELECT statement is

The purpose of a query is to answer a question.

A SELECT command is also known as a query. The SELECT command is used to gather information about the data contained in a database. See the post at to set up the database on your system. In each case, I will use the “TeamProject” database for my example queries. I will start with the basics and work my way up to the more complicated. Today, I begin the first of several posts on creating SQL queries in LibreOffice.

Basic sql query syntax