Query

• SELECT - extracts data from a database

  • SELECT * FROM {table_name};
  • SELECT {column1,column2, …} FROM {tablename}_;
  • SELECT DISTINCT {column1,column2, …} FROM {tablename}_;
  • Distinct ⇒ 중복값 제거
  • SELECT count(*) From table_name;
  • Example
  • SELECT Count(*) AS DistinctCountriesFROM (SELECT DISTINCT Country FROM Customers);

• WHERE Syntax - WHERE절은 여기저기서 다쓰입니다(update, delete 등)

  • OPERATOR TABLE

  operator

• The SQL AND, OR and NOT Operator

  • SELECT {column1,column2, …} FROM {tablename}_ WHERE {condition1} AND {condition2} AND {condition3 …};
  • SELECT {column1, column2, …} FROM {tablename}_ WHERE {condition1} OR {condition2} OR {condition3 …};
  • SELECT {column1,column2, …} FROM {tablename}_ WHERE NOT {condition};

• The SQL ORDER BY Keyword

  • ORDER BY는 오름차순(ascending), 내림차순(descending)으로 정렬
  • SELECT {column1, column2, …} FROM {table_name} ORDER BY {column1, column2, … } ASC|DESC;
  • SELECT * FROM Customers ORDER BY Country ASC, CustomerName DESC;

• The SQL INSERT INTO Statement

  • INSERT INTO table_name (column1, column2, column3, …) VALUES (value1, value2, value3, …);
  • INSERT INTO table_name (column1, column2, column3, …) VALUES (value1, value2, value3, …);

• SQL Wildcard Characters

  • Wildcard Char in MS Access
  • Wildcard Char in SQL Server

  Wildcard Char in SQL Server

• SQL Aliases

  • 임시적으로 테이블, 컬럼 이름을 지정하는데 사용함
  • Alias Column Syntax
  • SELECT columnname AS aliasname FROM table_name;
  • Alias Table Syntax
  • SELECT columnname(s) FROM tablename AS alias_name;
• UPDATE - updates data in a database
• DELETE - deletes data from a database
• INSERT INTO - inserts new data into a database
• CREATE DATABASE - creates a new database
• ALTER DATABASE - modifies a database
• CREATE TABLE - creates a new table
• ALTER TABLE - modifies a table
• DROP TABLE - deletes a table
• CREATE INDEX - creates an index (search key)
• DROP INDEX - deletes an index