SQL keywords are the reserved words for SQL operations. These Keywords are used across SQL version for different functionalities.
SQL keywords are case insensitive. So the keyword SELECT and select will behave in the same way. Let’s look at some of the commonly used SQL keywords.
- ALTER TABLE: ALTER TABLE is used for altering column of a table.
12345ALTER TABLEtable_nameADD column datatype;
Output: On execution of this command a column will get added to the table table_name.
- AND: AND is an sql operator which is used for adding multiple condition. If the conditions are satisfied by a row. It will be part of the result set.
123456SELECT column_nameFROM table_nameWHERE column1 = value1AND column2 = value2;
Output: On execution of this command, if column1 is equal to value1 and column2 is equal to value2 then only the row will be qualified for result set.
- AS: AS is used for aliasing a column or table.
1234SELECT column_name AS 'Alias'FROM table_name;
Output: On execution of this command, the result will display column_name as ‘Alias’.
- AVG: AVG is an aggregate function which will provide the average of the numeric column.
123SELECT AVG(column_name) FROM table_name;
Output: Execution of this command will provide the average of column_name.
- BETWEEN: BETWEEN is an operator which is used for defining a set. The value for range can be numeric, text and date.
12345SELECT column_name(s)FROM table_nameWHERE column_name BETWEEN value1 AND value2;
Output: Execution of this command will give a result set bounded by value1 and value2.
- COUNT: COUNT is a function which provides the count of the row for a column. The column should be a not null column.
123SELECT COUNT(column_name) FROM table_name;
Output: On execution of this command, the result will contain the count of the rows for column_name.
- CREATE TABLE: This command is used to create table in the database. It allows to specify the name of the table along with the name a datatype of the column.
123CREATE TABLE table_name (column1 datatype, column2 datatype);
Output: Execution of this command will result in creation of table with name as table_name along with column1 and column2 as the columns of the table.
- DELETE: DELETE is the command which is used for removing rows from the table
123DELETE FROM table_name WHERE column_name = value;
Output: On execution of this command the rows that will be selected based on the condition in the WHERE clause will be deleted.
- GROUP BY: GROUP BY is a clause in SQL that is only used with aggregate functions. It is used along with the SELECT statement to arrange identical data into groups.
12345SELECT COUNT(*)FROM table_nameGROUP BY column_name;
Output: Execution of this order will result in grouping the result set based on the column_name.
- INNER JOIN: INNER JOIN will select records with matching values in two tables.
12345SELECT column_name FROM table_1INNER JOIN table_2ON table_1.column_name = table_2.column_name;
Output: Above command will result in rows where both tables have matching values for column_name.
- INSERT: INSERT is used for adding a new row in the table.
123INSERT INTO table_name (column1, column2, column3) VALUES (value1, 'value2', value3);
Output: Execution of this command will result in addition of a new row with values corresponding to the columns.
- LIKE: LIKE is an operator which is used for specifying a pattern. This operator is used along with WHERE clause.
12345SELECT column_nameFROM table_nameWHERE column_name LIKE pattern;
Output: Output will the rows that will satisfy the like pattern.
- LIMIT: LIMIT is a clause which allows the restricting the result set rows to maximum number specified by the limit clause.
12345SELECT column_nameFROM table_nameLIMIT number;
Output: The resultset will be limited by the number that is provided as part of the limit clause.
- MAX: MAX is a function that will return the max value from the column specified.
1234SELECT MAX(column_name)FROM table_name;
Output: The output will the maximum value specified in the column column_name.
- MIN: MIN is a function that will return the min value from the column specified.
1234SELECT MIN(column_name)FROM table_name;
Output: The output will the minimum value specified in the column column_name.
- OR: OR is the operator that is used for selecting the rows based on satisfaction of either condition in WHERE clause.
123456SELECT column_nameFROM table_nameWHERE column_name = value1OR column_name = value2;
Output: Result set will contain rows where column_name value will be either value1 or value2.
- ORDER BY: ORDER BY is used for sorting of columns in ascending or descending order numerically or in alphabetical order.
12345SELECT column_nameFROM table_nameORDER BY column_name ASC;
Output: On execution of the command above we will get the result set in ascending order.
- LEFT JOIN, RIGHT JOIN: These will combine rows from different tables even if the join condition is not met. Every row in the left/right table is returned in the result set, and if the join condition is not met, then NULL values are filled in the columns from the left/right table.
12345SELECT column_name(s) FROM table_1LEFT JOIN table_2ON table_1.column_name = table_2.column_name;
Output: Execution of the command above will result in rows from the table_1 along with rows which satisfies the condition from table_212345SELECT column_name(s) FROM table_1RIGHT JOIN table_2ON table_1.column_name = table_2.column_name;
Output: Execution of the command above will result in rows from the table_2 along with rows which satisfies the condition from table_1.
- ROUND: ROUND is a function that rounds of the number specified in the column based on the integer that is specified as part of the function.
1234SELECT ROUND(column_name, integer)FROM table_name;
Output: The output of the command will result in rounding up the number based on the integer that is provided as part of the function.
- SELECT: SELECT is used to fetch the data from the data base.
123SELECT column_name FROM table_name
Output: On execution of this command the result set will contain rows for column column_name.
- SELECT DISTINCT: SELECT DISTINCT is used for retrieving distinct values from the column that is specified.
123SELECT DISTINCT column_name FROM table_name;
Output: On execution of the command above the result set will only contain the unique values from the column column_name.
- SUM: SUM is a function will provides the total value of a column which is numeric.
1234SELECT SUM(column_name)FROM table_name;
Output: Execution of this command will result in the total of all the row that are part of the column column_name.
- UPDATE: UPDATE is used for updating values of a row of a table.
12345UPDATE table_nameSET some_column = some_valueWHERE some_column = some_value;
Output: Execution of this command will result in updating the row that will satisfy the condition in the where clause.
- WHERE: WHERE is used for specifying the condition that should be satisfied for selecting the row to be part of the result set.
12345SELECT column_nameFROM table_nameWHERE column_name operator value;
Output: The output of this command will result in the rows that are satisfying the where clause.
That’s all for a quick roundup on mostly used SQL keywords.
Reference: Oracle SQL Reserved Words List