Basic SQL*Plus edit and execute commands SQL*Plus buffer and built-in editor holds the last SQL statement Statements are created in free-flow style and are numbered Example: select Custnumb, Balance from CUSTOMER The semicolon indicates the end of the SQL statement and causes execution A builtin editor is used to change the statements in the buffer after it has been created Append Credlim to the current listing Change the SELECT statement to return Custname rather than Custnumb

Basic SQL*Plus edit and execute commands contd. Insert a new line ORDER BY SLSRNUMB after the current line List the current statement in the buffer Formatting columns

Basic SQL*Plus edit and execute commands contd. The SQL statement in the buffer can be saved to a file A file may contain any number of SQL statements Comments: --for a single line of text /* for multi-line texts */ Editing and running a file

Table: columns, rows Valid Oracle object names must be unique <= 30 characters not a reserved word must start with a letter can contain letters, digits, some special characters (_,$,#) Data types for columns: VARCAHR2 variable length character string up to 2000 characters must specify length-- Example: slname VARCHAR2 (30) CHAR fixed length character string up to 255 characters should not be used if exact length is not known NUMBER: integer, fixed point, floating point numbers INTEGER: whole numbers Example: sid number(5) fixed-point numbers: price NUMBER (5,2) floating point numbers: gpa NUMBER Database tables

Database tables cont’d Data types cont’d DATE: no length specification needed. Various format masks can be used LONG: used for very large character data. Do not use RAW/LONG RAW: used for binary data--digitized image. Integrity constraints Primary key: sid NUMBER (5) CONSTRAINT student_pk PRIMARY KEY Foreign key: locid NUMBER (5) CONSTRAINT faculty_fk REFERENCES location(locid) Value constraints check that gpa is between 0 and 4 gpa NUMBER (5,2) CONSTRAINT gpa_cc CHECK gpa between 0 and 4 Creating/modifying/dropping tables: CREATE TABLE ( [CONSTRAINT ],....) Example: CREATE TABLE location (locid number (5) CONSTRAINT location_pk PRIMARY KEY......); DROP TABLE Example: DROP TABLE location;

Database tables cont’d Viewing table structure field definition: describe Example: Constraint definition user_constraints table Modifying tables changing a columns size, data type, default value adding/deleting PK, FK constraints deleting column/changing column name--not allowed adding a new column

Database tables cont’d Modifying table definitions Adding column/constraints ALTER TABLE ADD ( / ) Modifying existing table ALTER TABLE MODIFY ( / ) Dropping constraints ALTER TABLE DROP CONSTRINT