Data Constraints or Integrity Constraints
Integrity constraints or Data constraints Types 1.NOT NULL 2.UNIQUE 3.PRIMARY KEY 4.DEFAULT 5.CHECK 6.FORIEGN KEY OR REFERENCIAL INTEGRITY 1. NOT NULL : - Data must enter and duplicate values allowed Ø Create table student (Sno number constraint Sno_NN NOT NULL); 2. UNIQUE : -no duplicate value allowed and null value allowed Column level Ø Create table student (Sno number constraint Sno_UNQ UNIQUE); Table level Ø Create table student (Sno number, Name varchar2(100), constraint Sno_NM_UNQ UNIQUE (Sno, Name)); 3. PRIMARY KEY : -It will not accept null, duplicate values. Only one Primary key allowed on one table Column level Ø Create table student (Sno number constraint Sno_PK PRIMARY KEY); Table level Ø Create table student (Sno number, Name varchar2(100), constraint Sno_NM_PK PRIMARY KEY (Sno, Name)); 4. DEFAULT : - Ø Create table student (Sno number, J_Date date constraint JOD_DF DEFAULT sysdate);...