Podcast
Questions and Answers
Which category of SQL commands includes operations for creating and modifying database structures?
Which category of SQL commands includes operations for creating and modifying database structures?
- Data Query Language (DQL)
- Data Definition Language (DDL) (correct)
- Data Manipulation Language (DML)
- Data Control Language (DCL)
Which SQL command is used to modify data within a table?
Which SQL command is used to modify data within a table?
- Update (correct)
- Create
- Grant
- Alter
What is the correct way to add a single-line comment in SQL?
What is the correct way to add a single-line comment in SQL?
- /* Comment */
- // Comment
- -- Comment (correct)
- # Comment
Which of the following is true regarding case sensitivity in SQL?
Which of the following is true regarding case sensitivity in SQL?
Which SQL command is used to remove a table from the database?
Which SQL command is used to remove a table from the database?
Which of the following is the correct way to enclose date values in an SQL WHERE clause?
Which of the following is the correct way to enclose date values in an SQL WHERE clause?
Which DCL command is used to grant permissions to users?
Which DCL command is used to grant permissions to users?
What type of values are not enclosed in quotes in a WHERE clause?
What type of values are not enclosed in quotes in a WHERE clause?
Which command is used to retrieve data from a database?
Which command is used to retrieve data from a database?
What is the purpose of the SQL ALTER command?
What is the purpose of the SQL ALTER command?
Flashcards
SQL
SQL
A standard language for relational database management systems, used for managing and querying data.
Data Definition Language (DDL)
Data Definition Language (DDL)
Commands that define a database, including creating, altering, and dropping tables and establishing constraints.
Data Manipulation Language (DML)
Data Manipulation Language (DML)
Commands used to maintain and query a database, allowing users to interact with the data stored within the database.
Data Control Language (DCL)
Data Control Language (DCL)
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SQL Case Sensitivity
SQL Case Sensitivity
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SQL Single-Line Comment
SQL Single-Line Comment
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SQL Data Type Quotes
SQL Data Type Quotes
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Oracle Default Date Format
Oracle Default Date Format
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Study Notes
- SQL (Structured Query Language) was initially developed by IBM Research Lab in the 1970s to showcase the relational model of database systems.
- Originally named Sequel, it was later renamed SQL.
- SQL is the standard language for relational database management systems.
- The SQL standard has undergone numerous revisions, leading to variations in commands and interpretations across different database products.
Types of SQL Commands
- Data Definition Language (DDL) commands define a database, involving creating, altering, and dropping tables, as well as establishing constraints.
- Data Manipulation Language (DML) commands are used to maintain and query a database.
- Data Control Language (DCL) commands manage a database, including administering privileges and committing data.
Common SQL Commands
- DDL includes: Create, Drop, Alter, Rename
- DML includes: Select, Update, Insert, Delete
- DCL includes: Grant, Revoke
Writing SQL Statements
- SQL statements are not case sensitive, except for expressions within quotation marks.
- SQL statements can span one or more lines.
- Clauses are typically placed on separate lines for clarity.
- Keywords must not be split across lines.
- Tabs and spaces are permitted to enhance readability.
- Each SQL statement concludes with a semicolon (;).
SQL Comments
- Single-line comments begin with --.
- Multi-line comments are enclosed by /* and */.
WHERE Clause Criteria
- Text values are enclosed in single quotes.
- Dates are enclosed in single quotes.
- Numerical values are not enclosed in quotes.
- Text values are case sensitive.
- Date values are format sensitive.
- Oracle’s default date format is DD-MON-YY.
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