SQL Commands
作者：Yi Qian Chuah
1. Constraints
1.1. NOT NULL
1.2. UNIQUE
1.3. PRIMARY KEY
1.4. FOREIGN KEY
1.5. CHECK
1.6. DEFAULT
1.7. INDEX
2. Aggregate
2.1. COUNT
2.2. MIN
2.3. MAX
2.4. SUM
2.5. AVG
3. Comparison
3.1. =
3.2. <
3.3. <=
3.4. >
3.5. >=
3.6. !=
4. Special
4.1. IN
4.2. LIKE
4.3. BETWEEN
4.4. IS NULL
4.5. EXIST
5. Functions
5.1. DDL
5.1.1. CREATE
5.1.2. ALTER
5.1.3. DROP
5.2. DML
5.2.1. SELECT
5.2.2. UPDATE
5.2.3. INSERT
5.2.4. DELETE
5.2.5. ORDER BY
5.2.6. GROUP BY
5.2.7. WHERE
6. Data Types
6.1. Numeric
6.1.1. NUMBER (L,D)
6.1.2. INTEGER
6.1.3. DECIMAL (L,D)
6.2. Character
6.2.1. VARCHAR (L)
6.2.2. CHAR (L)