SQL stands for Structure Query Language. It is a programming language for storing and processing data systematically in a relational database. It was developed in the 1970s. It is used by database management administrators, web developers, and data analysts to run scripts and analytical queries.
The structured query language, SQL, became the International Organization for Standardization (ISO) standard in 1987. It is one of the most preferred choices of database administrators and analysts as it is easily available, and the functions can be efficiently carried out on vast data stores.
SQL is a type of command written in the form of statements directed into programs that allow users to access, add, and modify databases.
SQL table is the basic unit of SQL. It has multiple rows and columns of data. A relational database is called so as the SQL tables are related to each other. Each tab in the table holds certain records of related data.
Keywords and Elements Used in Creating SQL
Before we proceed with learning how to create SQL tables, let us get familiar with certain keywords and elements used in the programming language.
1. Keywords - Keywords are words that allow one to find similar ones in the datasheet or the SQL table. For example, the keyword “employee” will search similar patterns or words in the database.
If you want to find or identify the employee with the last name “Malhotra,” the keyword will enable you to fetch the names of the employees with the last name ‘Malhotra” within seconds.
2. Expressions - They are the operators, functions, and values that enable you to evaluate a particular value in the datasheet. SQL expressions are broadly divided into three types: numeric, Boolean, and date.
3. SQL queries - SQL queries refer to certain commands written in the form of statements used to retrieve particular data from the database.
4. Clauses - clauses are the already-in-built functions in the SQL that filter the given data and bring out the relevant and required ones. Clauses are the most useful elements in the structured query language while handling and dealing with vast amounts of data.
A Step–by–step Process to Creating SQL Tables.
Let's see an SQL example to understand better.
Start by naming the SQL table; for instance, the name of this table would be ‘employee’
The table with include components – the employee ID, employee name, salary, age, gender, and the department he/she is working.
Define the columns of the SQL table
Name a data type for every column that you see in the table.
Syntax of creating the SQL table
CREATE TABLE table name
Column 1 datatype,
Column 2 datatype,
Column n data type,
Primary key (1/< columns));
Here, CREATE TABLE is the primary keyword, and the table name is the table's name.
In this SQL example, the table name as named earlier is ‘Employee’
Columns 1 to column n are the set of columns and their data type followed by a semicolon.
Create the table, employee(
e_id int not null,
e_ name varchar (20),
e_gender varchar (20),
e_dept varchar (20),
primary key (e_id));
- In the syntax above, e-id means employee ID, e_name refers to the employee name, e_salary for the salary of the employee,
- e_age stands for the employee's age,
- e_gender for the gender of the concerned employee, and the e_dept refers to the department the employee works for.
- Varchar (20) is the string length you would insert in the table tab.
- Not null signifies that every cell has some value; it is not 0 or null.
- The primary key identifies all the given records from a concerned SQL table. There cannot be more than one primary key in a table.
- Once the query is written, the user has to click on the execute button to verify if there is any error.
- After the query is executed completely and successfully, a popup says, ‘Commands completed successfully.’
- It is used for deleting tables.
- The “DROP” command must be used from the data definition language to delete a table.
- The data definition language is considered to be the sub-language of SQL that allows access, create and modify the table and its data structure.
- While deleting a table or a column or row, you have to be careful, as once deleted, you cannot retrieve any record from the deleted table.
For instance, if we do not require the table name employee gender anymore,
The syntax would be;
Mysql> DROP TABLE employee_gender;
Query OK, 0 rows affected.
The table you do not require is deleted now and can be checked using the “DESC” command.
Mysql> DESC employee_gender;
ERROR 1147: Table ‘our_database.employee_gender’ doesn’t exist
Hence, it can be seen that the table does not exist and has been permanently deleted from the database.
Uses of SQL
- It helps in managing relational databases
- It performs the basic operational functions such as search, filter, sort, create, drop, and alter most efficiently.
- It provides developers with the compatibility and flexibility to access and manipulate any table in the database. It can easily manage large stores of data on a website with quite ease.
In a nutshell, learning SQL table creation is essential for efficient data management. You now have the essential syntax and examples that clear keywords, expressions, and queries. You are prepared to apply this knowledge to numerous database activities if you have practical insights into designing tables, such as the example of the "Employee" table. Remember that this journey goes beyond establishing tables, allowing you to optimize, query, and create with data. Use SQL's capabilities as you help create effective data structures that advance numerous industries.
What is SQL, and why is it important in the world of databases?
A programming language called SQL, or Structured Query Language, is used to store and process data in relational databases. Managing data successfully using SQL queries and scripts is essential for database administrators, web developers, and data analysts.
What are the key elements used in SQL programming?
Keywords (used to look for repeated patterns in the data), expressions (operators, functions, and values for evaluating data), SQL queries (commands to retrieve certain data), and clauses (built-in functions to filter and extract pertinent information) are important components.
Can you explain the process of creating a SQL table step by step?
Name the table and specify its columns first. Indicate the data types for each column, such as string for varchar or integer for integer. To construct the table, use the construct TABLE statement with the table name and column specifications. Setting a primary key will allow records to be uniquely identified.
What's the syntax for creating an SQL table?
CREATE TABLE table_name (
PRIMARY KEY (one_or_more_columns)
The table name, column names, data types, and a primary key to identify records are all defined in this structure.
How do you drop (delete) a SQL table, and what should you be cautious about?
Use the DROP command to drop a table. The data in discarded tables cannot be retrieved; therefore, exercise caution. You might use the command DROP TABLE employee_gender to remove a table with the name "employee_gender," for instance. Before using the DROP command, double-check everything.