MySQL Basics

Author: learning-zone

sql-commands.md

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+## MySQL Basics 
+
+### ALTER TABLE
+
+```
+ALTER TABLE table_name ADD column datatype;
+```
+
+`ALTER TABLE` lets you add columns to a table in a database.
+
+### AND
+
+```
+SELECT column_name(s)
+FROM table_name
+WHERE column_1 = value_1
+AND column_2 = value_2;
+```
+
+`AND` is an operator that combines two conditions. Both conditions must be true for the row to be included in the result set.
+
+### AS
+
+```
+SELECT column_name AS 'Alias'
+FROM table_name;
+```
+
+`AS` is a keyword in SQL that allows you to rename a column or table using an *alias*.
+
+### AVG
+
+```
+SELECT AVG(column_name)
+FROM table_name;
+
+```
+
+`AVG()` is an aggregate function that returns the average value for a numeric column.
+
+### BETWEEN
+
+```
+SELECT column_name(s)
+FROM table_name
+WHERE column_name BETWEEN value_1 AND value_2;
+```
+
+The `BETWEEN` operator is used to filter the result set within a certain range. The values can be numbers, text or dates.
+
+### COUNT
+
+```
+SELECT COUNT(column_name)
+FROM table_name;
+```
+
+`COUNT()` is a function that takes the name of a column as an argument and counts the number of rows where the column is not `NULL`.
+
+### CREATE TABLE
+
+```
+CREATE TABLE table_name (column_1 datatype, column_2 datatype, column_3 datatype);
+```
+
+`CREATE TABLE` creates a new table in the database. It allows you to specify the name of the table and the name of each column in the table.
+
+### DELETE
+
+```
+DELETE FROM table_name WHERE some_column = some_value;
+```
+
+`DELETE` statements are used to remove rows from a table.
+
+### GROUP BY
+
+```
+SELECT COUNT(*)
+FROM table_name
+GROUP BY column_name;
+```
+
+`GROUP BY` is a clause in SQL that is only used with aggregate functions. It is used in collaboration with the `SELECT` statement to arrange identical data into groups.
+
+### INNER JOIN
+
+```
+SELECT column_name(s) FROM table_1
+JOIN table_2
+ON table_1.column_name = table_2.column_name;
+```
+
+An inner join will combine rows from different tables if the *join condition* is true.
+
+### INSERT
+
+```
+INSERT INTO table_name (column_1, column_2, column_3) VALUES (value_1, 'value_2', value_3);
+```
+
+`INSERT` statements are used to add a new row to a table.
+
+### LIKE
+
+```
+SELECT column_name(s)
+FROM table_name
+WHERE column_name LIKE pattern;
+```
+
+`LIKE` is a special operator used with the `WHERE` clause to search for a specific pattern in a column.
+
+### LIMIT
+
+```
+SELECT column_name(s)
+FROM table_name
+LIMIT number;
+```
+
+`LIMIT` is a clause that lets you specify the maximum number of rows the result set will have.
+
+### MAX
+
+```
+SELECT MAX(column_name)
+FROM table_name;
+```
+
+`MAX()` is a function that takes the name of a column as an argument and returns the largest value in that column.
+
+### MIN
+
+```
+SELECT MIN(column_name)
+FROM table_name;
+```
+
+`MIN()` is a function that takes the name of a column as an argument and returns the smallest value in that column.
+
+### OR
+
+```
+SELECT column_name
+FROM table_name
+WHERE column_name = value_1
+OR column_name = value_2;
+```
+
+`OR` is an operator that filters the result set to only include rows where either condition is true.
+
+### ORDER BY
+
+```
+SELECT column_name
+FROM table_name
+ORDER BY column_name ASC|DESC;
+```
+
+`ORDER BY` is a clause that indicates you want to sort the result set by a particular column either alphabetically or numerically.
+
+### OUTER JOIN
+
+```
+SELECT column_name(s) FROM table_1
+LEFT JOIN table_2
+ON table_1.column_name = table_2.column_name;
+```
+
+An outer join will combine rows from different tables even if the the join condition is not met. Every row in the *left* table is returned in the result set, and if the join condition is not met, then `NULL` values are used to fill in the columns from the *right* table.
+
+### ROUND
+
+```
+SELECT ROUND(column_name, integer)
+FROM table_name;
+```
+
+`ROUND()` is a function that takes a column name and an integer as an argument. It rounds the values in the column to the number of decimal places specified by the integer.
+
+### SELECT
+
+```
+SELECT column_name FROM table_name;
+```
+
+`SELECT` statements are used to fetch data from a database. Every query will begin with SELECT.
+
+### SELECT DISTINCT
+
+```
+SELECT DISTINCT column_name FROM table_name;
+```
+
+`SELECT DISTINCT` specifies that the statement is going to be a query that returns unique values in the specified column(s).
+
+### SUM
+
+```
+SELECT SUM(column_name)
+FROM table_name;
+```
+
+`SUM()` is a function that takes the name of a column as an argument and returns the sum of all the values in that column.
+
+### UPDATE
+
+```
+UPDATE table_name
+SET some_column = some_value
+WHERE some_column = some_value;
+```
+
+`UPDATE` statments allow you to edit rows in a table.
+
+### WHERE
+
+```
+SELECT column_name(s)
+FROM table_name
+WHERE column_name operator value;
+```
+
+`WHERE` is a clause that indicates you want to filter the result set to include only rows where the following *condition* is true.