30 Questions
What is the purpose of the INSERT INTO statement in SQL?
to insert new row(s) into a database table
What happens to the values of columns when they are not specified during row insertion?
they will be NULL
What is the syntax to insert multiple rows at once in SQL?
using multiple VALUES clauses separated by commas
What is the purpose of the UPDATE statement in SQL?
to modify existing records in a database table
What is required to update a single value in a row using the UPDATE command?
a WHERE clause
What is the syntax to update multiple columns in a single row?
UPDATE table_name SET column1 = value1, column2 = value2, ...
What is the purpose of the UPDATE statement in SQL, and how can it be used to update multiple values in a single row?
The UPDATE statement is used to modify existing data in a table. It can be used to update multiple values in a single row by separating the column-value pairs with commas, as in UPDATE Customers SET first_name = 'Johnny', last_name = 'Depp' WHERE customer_id = 1;
How can you update multiple rows in a table at once using the UPDATE statement?
You can update multiple rows in a table at once by specifying a condition in the WHERE clause that selects multiple rows, as in UPDATE Customers SET country = 'NP' WHERE age = 22;
What is the difference between the DELETE and TRUNCATE TABLE statements in SQL?
The DELETE statement is used to delete rows from a table based on a condition, while the TRUNCATE TABLE statement is used to delete all rows from a table at once, without the need for a condition.
How can you delete a single row from a table using the DELETE statement?
You can delete a single row from a table by specifying a condition in the WHERE clause that selects a single row, as in DELETE FROM customers WHERE id = 5;
What is the effect of omitting the WHERE clause in a DELETE statement?
Omitting the WHERE clause in a DELETE statement will delete all rows from the table.
How can you update all rows in a table at once using the UPDATE statement?
You can update all rows in a table at once by omitting the WHERE clause, as in UPDATE Customers SET country = 'NP';
What is the primary difference between the SQL TRUNCATE and SQL DELETE statements when it comes to removing records from a table?
TRUNCATE can only remove all the records from a table, whereas DELETE can remove single, multiple, or all rows/records from a table.
What is the purpose of the SQL SELECT statement?
The SQL SELECT statement is used to select (retrieve) data from a database table.
How do you select all columns from a database table in SQL?
You can select all columns from a database table using the * character.
What is the purpose of the WHERE clause in a SQL SELECT statement?
The WHERE clause allows us to fetch records from a database table that matches specified condition(s).
How do you enclose textual data in SQL statements?
You must enclose textual data inside either single or double quotations.
What is the difference between the SQL TRUNCATE and SQL DELETE statements in terms of supporting the WHERE clause?
SQL DELETE supports the WHERE clause, whereas SQL TRUNCATE does not support the WHERE clause.
What is the effect of using the DISTINCT keyword with the COUNT() function in SQL?
It counts the number of unique rows.
What is the purpose of the AS keyword in SQL?
It is used to give columns or tables a temporary name.
How do you give a column a temporary name in SQL?
Using the AS keyword, for example: SELECT first_name AS name FROM Customers;
What does the LIMIT keyword do in SQL?
It allows us to specify the number of records in the result set.
What is the purpose of the OFFSET keyword in SQL?
It is used to specify the starting rows from where to select the data.
How do you combine the LIMIT and OFFSET keywords in SQL?
For example: SELECT first_name, last_name FROM Customers LIMIT 2 OFFSET 3;
What is the purpose of the WHERE clause in SQL, and provide an example of its usage?
The WHERE clause is used to construct conditions using operators to filter data. For example, SELECT * FROM Customers WHERE first_name = 'John';
Explain the difference between the AND and OR operators in SQL, and provide an example of each.
The AND operator is used to combine two conditions where both must be true, whereas the OR operator is used to combine two conditions where at least one must be true. For example, SELECT * FROM Customers WHERE last_name = 'Doe' AND country = 'USA'; and SELECT * FROM Customers WHERE last_name = 'Doe' OR country = 'USA';
How can you combine multiple AND, OR, and NOT operators in an SQL statement, and provide an example?
You can combine multiple AND, OR, and NOT operators using parentheses to group conditions. For example, SELECT * FROM Customers WHERE (country = 'USA' OR country = 'UK') AND age < 26;
What is the purpose of the SELECT DISTINCT statement in SQL, and provide an example?
The SELECT DISTINCT statement is used to retrieve distinct values from a database table. For example, SELECT DISTINCT age FROM Customers;
How can you use SELECT DISTINCT with multiple columns, and provide an example?
You can use SELECT DISTINCT with multiple columns by separating them with commas. For example, SELECT DISTINCT country, first_name FROM Customers;
What is the difference between using the SELECT statement with and without the DISTINCT keyword?
The SELECT statement without the DISTINCT keyword returns all rows, including duplicates, while the SELECT DISTINCT statement returns only unique values.
Test your knowledge of the SQL INSERT INTO statement, used to insert new rows into a database table. Learn the syntax and practices of creating new records in a database.
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