It's time to write our very first database query. Learn how to retrieve all rows and all columns from a database table using a SQL query.
- [Instructor] All right, so now it's time for us to write our very first SQL query. For our first query we'll try and keep things as simple as possible. Every SQL commander where you wish to retrieve data from database tables start with the select keyword. I'm writing select in uppercase just for legibility purposes, but you can lowercase as well. So select signifies which columns I want to retrieve from my table.
Note that I haven't specified the table name just yet. To select all of the columns the columns in the table, all I have to do is type the star character. We'll see how we can select individual columns later on. Going down one line I can specify from which table I want to select my columns. So I'll type from and the table name, for example, employees. Note that similarly to the select keyword, I've also specified the from keyword in uppercase, but you can use lowercase as well.
Again, I'm using uppercase just for legibility purposes. We can now highlight this query and press the green play button, which will execute it. We will see the results presented in the bottom part of our screen. We can see a long list of rows with multiple columns representing all of the data in our table. Because I've typed the select star command from employees, I'm instructing the Oracle database to return all columns using the star keyword from the employees tables without filtering for any specific rows.
We will see how we can filter rows later on.
Note: This training course is appropriate for beginning database developers with no prior experience with SQL or Oracle.
- Using Oracle SQL*Developer, the free development environment
- Selecting data from tables
- Filtering data
- Using functions to manipulate data
- Joining data from tables
- Creating tables
- Updating values
- Truncating data
- Grouping and ordering result sets
- Working with primary keys
- Checking constraints
Skill Level Beginner
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1. Introduction to SQL
2. Preparing the Course Environment
Downloading the course VM2m 16s
3. Using Oracle SQL Developer
4. Basic SELECT Queries
5. String, Number, and Date Functions
6. Joining Table Data
7. Manipulating Data
8. Grouping Data
9. Advanced Topics
Next steps1m 33s
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