SQL SELECT Statement — Retrieving Data from Tables

The office needs student names and cities for class 10A, rather than every field of every student.

SELECT produces a result from expressions and table data. Choosing columns changes the report’s shape; filtering rows changes which records contribute.

FROM supplies the row source, WHERE applies a condition when present, and the SELECT list chooses the returned expressions. The displayed result is a report, not an automatic change to the stored table. An expression or alias can produce a result column that is not itself a new stored column.

Related concepts: Filter with WHERE and Sort Results.

SQL · portable concepts; preserved examples identify their engine

SELECT column1, column2, ...
FROM table_name
WHERE condition;

where

• SELECT: A required keyword that begins the statement. It tells the database you want to retrieve data.
• column1, column2, ...: A comma-separated list of the columns you want to fetch from the table. You can also use * to select all columns.
• FROM: A required keyword that specifies where to look for the data — i.e., which table to select from.
• table_name: The actual name of the table containing the data.
• WHERE (optional): Used to filter the results based on a condition. Only rows that satisfy the condition will be returned.
• condition: The logical expression that decides which rows are included. For example, age > 15.
• ;: Ends the SQL statement. It is required by most SQL engines to separate one statement from another.

SQL · portable concepts; preserved examples identify their engine

Let’s use a simple students table as our base. We shall use this table in the following examples.

CREATE TABLE students (
  roll_no INT PRIMARY KEY,
  name VARCHAR(50),
  class VARCHAR(10),
  age INT,
  city VARCHAR(30)
);

INSERT INTO students VALUES
(1, 'Aarav Sharma', '10A', 15, 'Delhi'),
(2, 'Diya Iyer', '9B', 14, 'Chennai'),
(3, 'Rohit Menon', '10A', 15, 'Kochi'),
(4, 'Sneha Patil', '8C', 13, 'Pune');

SQL · portable concepts; preserved examples identify their engine

SELECT * FROM students;

This retrieves everything — every row, every column.

SQL · portable concepts; preserved examples identify their engine

Say, we need only the name and city columns from the students table.

SQL query to select only the name and city columns from the students table.

SELECT name, city FROM students;

This query returns only the name and city columns for all the records in the students table.

The surrounding query explains the specific highlighted values. Highlights annotate this example; they do not change the stored table.

SQL · portable concepts; preserved examples identify their engine

Retrieve all the student records who belong to class 10A.

SQL Query to select all records from the students table where the value in the class column is equal to '10A'.

SELECT * FROM students
WHERE class = '10A';

The result includes all columns—roll_no, name, class, age, and city—for students who are in class 10A. In this case, it shows the complete information of students Aarav Sharma and Rohit Menon who are both enrolled in class 10A.

The surrounding query explains the specific highlighted values. Highlights annotate this example; they do not change the stored table.

SQL · portable concepts; preserved examples identify their engine

Use logical operators like AND and OR:

Get a list of student names from class 10A who are located in Kochi, perhaps to organize a local class event or distribute location-specific announcements.

SQL statement to select the names of all students who are in class 10A and live in the city of Kochi.

SELECT name FROM students
WHERE class = '10A' AND city = 'Kochi';

This query retrieves the name column from the students table, but only for those records where the class is '10A' and the city is 'Kochi'. In other words, it returns the names of students who meet both of these conditions.

The surrounding query explains the specific highlighted values. Highlights annotate this example; they do not change the stored table.

SQL · portable concepts; preserved examples identify their engine

Use Case: A teacher wants to view a list of student names along with their ages from the students table, sorted from the oldest to the youngest. This can help in identifying senior students for leadership roles or assigning age-appropriate responsibilities.

Select the name and age columns from the students table, and sort the results in descending order based on the age column. This means the oldest students will appear at the top of the result set.

SELECT name, age FROM students
ORDER BY age DESC;

The query returns the name and age of all students from the students table, sorted by age in descending order. This means students are listed from the oldest to the youngest. If multiple students share the same age, they appear in the order they were found in the table.

The surrounding query explains the specific highlighted values. Highlights annotate this example; they do not change the stored table.

SQL · portable concepts; preserved examples identify their engine

Use Case: A school administrator wants to know all the different classes present in the student records, without listing duplicates, in order to create a class-wise summary or generate a class list.

Select only the unique values from the class column in the students table using the DISTINCT keyword. This ensures that duplicate class names are removed from the result.

SELECT DISTINCT class FROM students;

Result Description: The result shows a list of distinct class names found in the students table. Based on the data, the classes returned would be: 10A, 9B, and 8C.

The surrounding query explains the specific highlighted values. Highlights annotate this example; they do not change the stored table.

SQL · portable concepts; preserved examples identify their engine

Use Case: A reporting system needs to display a list of student names and their hometowns with custom column headers for better readability or alignment with a specific format.

SQL Description: Select the name and city columns from the students table, and rename them in the output as student_name and hometown using the AS keyword.

SELECT name AS student_name, city AS hometown
FROM students;

Result Description: The output will show two columns: one labeled student_name containing the names of the students, and another labeled hometown containing their respective cities. This makes the data more descriptive and easier to interpret in external reports or user interfaces.

The surrounding query explains the specific highlighted values. Highlights annotate this example; they do not change the stored table.

SQL · portable concepts; preserved examples identify their engine

Use Case: A school administrator wants to prepare for next year's academic planning by viewing each student's age in the upcoming year. This helps in organizing age-specific activities or promotions.

SQL Description: Select the name and age columns from the students table, and also calculate a new column named next_year_age by adding 1 to the current age of each student. This column is given an alias using AS.

SELECT name, age, age + 1 AS next_year_age
FROM students;

Result Description: The result includes the student's name, their current age, and a computed column next_year_age which shows what their age will be next year. This is calculated by adding 1 to each student's current age.

The surrounding query explains the specific highlighted values. Highlights annotate this example; they do not change the stored table.

• Use SELECT * cautiously — avoid it in production queries.
• Filter your queries using WHERE to reduce load and noise.
• Use aliases for clarity in reports or views.

Without ORDER BY, the database does not promise the displayed order. SELECT * can return unnecessary or sensitive columns and changes shape when the schema changes. SELECT can also compute expressions without reading a table.

Return only name and city for class 10A, with a repeatable roll-number order.

This practice uses a separate, fresh fixture named practice_students. It does not continue the changing table state of the earlier examples.

SQL · create only these practice tables in a disposable database:

CREATE TABLE practice_students (roll_no INTEGER PRIMARY KEY, name VARCHAR(50), class VARCHAR(10), marks INTEGER, city VARCHAR(30));
INSERT INTO practice_students VALUES
(1, 'Aarav', '10A', 85, 'Pune'),
(2, 'Diya', '9B', 70, 'Chennai'),
(3, 'Sneha', '10A', 85, 'Pune');

This practice uses a separate, fresh fixture named practice_students. It does not continue the changing table state of the earlier examples.

SQL · create only these practice tables in a disposable database:

CREATE TABLE practice_students (roll_no INTEGER PRIMARY KEY, name VARCHAR(50), class VARCHAR(10), marks INTEGER, city VARCHAR(30));
INSERT INTO practice_students VALUES
(1, 'Aarav', '10A', 85, 'Pune'),
(2, 'Diya', '9B', 70, 'Chennai'),
(3, 'Sneha', '10A', 85, 'Pune');

SQL · this practice variation runs with SQLite 3; the preserved examples retain their stated dialect

SELECT name, city FROM practice_students WHERE class = '10A' ORDER BY roll_no;

The condition keeps two records, and the select list returns two fields for each. Neither operation changes the stored students table.

SELECT produces a result from expressions and table data. Choosing columns changes the report’s shape; filtering rows changes which records contribute.

The condition keeps two records, and the select list returns two fields for each. Neither operation changes the stored students table.

Continue your understanding with Filter with WHERE and Sort Results.

Source for the engine-specific behavior: MySQL 8.4 reference documentation.