![]() The last_name_count field doe not appear in the field list because it only contains table fields. Click on the " label on the left-hand side of the expression.That will insert an " = " expression label. Reopen the Query Builder and click the label beside the HAVING keyword.To do that we need to add the HAVING clause. What it doesn't do is limit the results to those actors who share their last name with at least two other actors. Here are the results produced by the above query:Īs you can see, the results are grouped and sorted by last_name. That will add the following SQL to the Query Editor: Click the OK button to close the Query Builder.To do that, click the label and choose the sakila.last_name field from the popup dialog. The next step is to add the GROUP BY clause.To add the Count function to the field list, click on the label underneath the sakila.last_name field in the SQL statement and enter "Count(*)" in the Edit tab of the popup dialog: Click the box beside the last_name field in the table: We will require two fields: the last_name and a count of rows. That will cause the actor table to appear in the top pane along with all of its fields.With that in mind, open the Query Builder, click on the label beside the FROM keyword, and choose the sakila.actor table from the list:.I find that whether I'm constructing a query using the Query Editor or the Query Builder, it's best to choose the tables first. ![]() If we wanted to know how many actors in our database share the same last name with at least two other actors, we could use the GROUP BY clause to aggregate actors according to the last_name field of the actors table. Determining How Many Actors Share the Same Last Name In contrast to the WHERE clause, which is applied before the GROUP BY clause, the HAVING clause applies a filter to rows AFTER they have been aggregated by the the GROUP BY clause. The SQL HAVING clause is used in combination with the GROUP BY clause to restrict the groups of returned rows based on one or more criteria. Filtering Result Groups with the HAVING Clause Please refer to the Generating Reports on MySQL Data tutorial for instructions on downloading and installing the Sakila database. It contains a number of tables themed around the film industry that cover everything from actors and film studios to video rental stores. The query that we'll be building here today will run against the Sakila sample database. This installment describes how to use the Query Builder to filter grouped data based on a HAVING condition. Part 4 described how to include native SQL aggregate functions in your queries to display column statistics. Available in Non-Essentials editions of Navicat for MySQL, PostgreSQL, SQLite, MariaDB, and Navicat Premium, the Query Builder is a tool for creating and editing queries visually.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |