Podcast
Questions and Answers
Which of the following is a Relational Database Management System (RDBMS)?
Which of the following is a Relational Database Management System (RDBMS)?
- MySQL
- Oracle
- Microsoft Access
- All of the above (correct)
What is the most common SQL statement used to retrieve data from a database?
What is the most common SQL statement used to retrieve data from a database?
- UPDATE
- SELECT (correct)
- CREATE
- INSERT
Which data type in SQL would you choose to store a specific date, such as 'July 4, 1776'?
Which data type in SQL would you choose to store a specific date, such as 'July 4, 1776'?
- INT
- FLOAT
- VARCHAR
- DATE (correct)
When constructing a query, which clause is used to specify a condition that filters the rows returned?
When constructing a query, which clause is used to specify a condition that filters the rows returned?
What is the fundamental operation performed by a JOIN clause in SQL queries?
What is the fundamental operation performed by a JOIN clause in SQL queries?
Which SQL keyword is employed to consolidate the result sets of two SELECT statements into a single result set?
Which SQL keyword is employed to consolidate the result sets of two SELECT statements into a single result set?
Which SQL command is used to permanently remove a table and all its data from a database?
Which SQL command is used to permanently remove a table and all its data from a database?
Which aggregate function in SQL would you use to determine the total number of rows in a table, including those with NULL values?
Which aggregate function in SQL would you use to determine the total number of rows in a table, including those with NULL values?
What operator is most commonly used within a WHERE clause to perform equality checks and comparisons of values?
What operator is most commonly used within a WHERE clause to perform equality checks and comparisons of values?
What is the primary effect of using the DISTINCT keyword in a SELECT statement?
What is the primary effect of using the DISTINCT keyword in a SELECT statement?
What key distinction differentiates an INNER JOIN from an OUTER JOIN in SQL?
What key distinction differentiates an INNER JOIN from an OUTER JOIN in SQL?
What critical role does a primary key serve within a database table?
What critical role does a primary key serve within a database table?
How does the ORDER BY clause affect the output of a SELECT statement?
How does the ORDER BY clause affect the output of a SELECT statement?
What fundamentally differentiates the UPDATE statement from the DELETE statement in SQL?
What fundamentally differentiates the UPDATE statement from the DELETE statement in SQL?
What is the defining characteristic of a subquery in SQL?
What is the defining characteristic of a subquery in SQL?
Which SQL statement demonstrates the correct syntax for creating a new table named 'Customers' with columns for 'CustomerID' (INT) and 'Name' (VARCHAR(255))?
Which SQL statement demonstrates the correct syntax for creating a new table named 'Customers' with columns for 'CustomerID' (INT) and 'Name' (VARCHAR(255))?
Which of the following functions in SQL operates on each row individually, rather than on a group of rows?
Which of the following functions in SQL operates on each row individually, rather than on a group of rows?
In a WHERE clause, what type of operation does the LIKE operator perform?
In a WHERE clause, what type of operation does the LIKE operator perform?
What is the primary role of the GROUP BY clause in a SELECT statement?
What is the primary role of the GROUP BY clause in a SELECT statement?
What does an alias represent in an SQL context?
What does an alias represent in an SQL context?
Flashcards
What is a RDBMS?
What is a RDBMS?
A system for managing relational databases.
What does SELECT do?
What does SELECT do?
Used to retrieve data from a database.
What is the DATE datatype?
What is the DATE datatype?
Best suited for storing dates.
What is the WHERE clause?
What is the WHERE clause?
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What does JOIN do?
What does JOIN do?
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What does UNION do?
What does UNION do?
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What does DROP TABLE do?
What does DROP TABLE do?
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What does COUNT do?
What does COUNT do?
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What does DISTINCT do?
What does DISTINCT do?
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What is a subquery?
What is a subquery?
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What is a database schema?
What is a database schema?
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What is an alias?
What is an alias?
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What does foreign key do?
What does foreign key do?
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What does HAVING do?
What does HAVING do?
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What distinguishes UNION?
What distinguishes UNION?
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UPDATE vs DELETE?
UPDATE vs DELETE?
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What is LIKE?
What is LIKE?
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True about TCL?
True about TCL?
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SQL data types?
SQL data types?
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Count(*) displays?
Count(*) displays?
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Study Notes
- MySQL, Oracle, and Microsoft Access are examples of Relational Database Management Systems (RDBMS).
- SELECT statement is the most common SQL statement to retrieve data from a database.
- DATE is the SQL data type best suited for storing dates.
- WHERE clause specifies a condition in a SELECT statement.
- JOIN operation combines data from two or more tables in SQL.
- UNION keyword combines the results of two or more SELECT statements.
- DROP TABLE command permanently deletes a table.
- COUNT function counts the number of rows in a table.
- The "=" operator is used for comparisons in the WHERE clause.
- DISTINCT keyword returns only unique values in a SELECT statement.
- INNER JOIN returns all matching rows, while OUTER JOIN returns all rows from one table.
- A primary key uniquely identifies each row in a table.
- ORDER BY clause sorts the results in a SELECT statement.
- UPDATE modifies existing data, while DELETE removes data entirely.
- A subquery is a query nested within another.
- CREATE TABLE table_name (column1 datatype, column2 datatype, ...) is the syntax for creating a new table in SQL.
- Concat, lower and upper are examples of single-row functions.
- The LIKE operator performs a pattern matching search in a WHERE clause.
- GROUP BY clause groups data based on one or more columns.
- An alias is a temporary name assigned to a table or column.
- A foreign key create a relationship between tables, enforcing referential integrity.
- HAVING clause filters groups based on a condition applied to aggregate functions in a SELECT statement used with GROUP BY.
- UNION removes duplicates, while UNION ALL keeps all rows.
- The symbol || represents a concatenation operator.
- UNION ALL is faster in terms of performance compared to UNION.
- Schema is a blueprint for the database structure, defining tables and their relationships, whereas tables store the actual data.
- Transactions can be saved to the database and rolled back using TCL commands in SQL.
- COMMIT statement saves the changes made within a transaction.
- ROLLBACK statement reverts all changes made within a transaction.
- Data types in SQL is used to specify the format and range of allowed values for a column.
- An inner join combines data from two tables, while a self-join joins a table to itself.
- Logical operators combine conditions, while comparison operators evaluate expressions.
- Functions in SQL is used to perform calculations or manipulations on data.
- Aggregate functions operate on groups of data, returning a single value, while scalar functions operate on individual values.
- "Select * from customer natural join order;" is equivalent to "Select * from customer join order on customer.customerid = order.customerid;".
- SELECT * FROM student WHERE name LIKE 'r%'; retrieves all data from student table starting the name from letter 'r'.
- SELECT * FROM customers; statement retrieves data from a table named "customers" and display all columns.
- SELECT * FROM customers WHERE id > 10; filters the results in the "customers" table to only show customers with an ID greater than 10.
- SELECT COUNT (*) FROM customers; SQL statement will display the number of customers in the "customers" table.
- SELECT name FROM customers ORDER BY name; retrieves the names of all customers from the "customers" table, sorted alphabetically (ascending order) by their names.
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