Oracle Definition Variables Summary

First, when you run the Scott password hint error in cmd, you can change this, and Scott's unlock command is:

To log on as a system user:
Cmd
Sqlplus System/tigertiger
Alter user Scott identified by "Tiger" account unlock;

-Learn the structure of blocks
--Learning to define variables (understanding data types) and assigning values
--Understanding: Types of various PL/SQL blocks

--the structure of the block
--Case: According to work number, output employee name
SELECT * from EMP;

--Block!
DECLARE
V_empno number (4);
V_ename VARCHAR2 (10);
BEGIN
V_empno: = & Please enter the work number;
--You must put the query result into a variable
SELECT ename to v_ename from EMP WHERE empno=v_empno;
Dbms_output.put_line (V_ename);
END;

--exception
DECLARE
V_empno number (4);
V_ename VARCHAR2 (10);
BEGIN
V_empno: = & Please enter the work number;
--You must put the query result into a variable
SELECT ename to v_ename from EMP WHERE empno=v_empno;
Dbms_output.put_line (V_ename);

EXCEPTION
When OTHERS Then
Dbms_output.put_line (' Doing something wrong, boss! ‘);
END;

--Summary
DECLARE
--Variable area (not at begin.) defined in end)
BEGIN
--Business code area
Excetipn
--anomaly capture area
END;

--Defining variables (Understanding data types)
--2: Save a value = simple variable; save multiple values = Compound variable

--Simple Variable type: char,varchar2,number,date (also column type), Boolean, table. Field%type
--Compound variable: Table%rowtype,record
DECLARE
V_empno number (4);
V_ename VARCHAR2 (10);
V_job Emp.job%type; --If the field type changes, the script does not need to change
BEGIN
V_empno: = 7566;
SELECT ename,job to v_ename,v_job from EMP WHERE empno=v_empno;
Dbms_output.put_line (V_ename);
IF (v_job= ' MANAGER ') then
Dbms_output.put_line (' manager, have you had dinner? ‘);
END IF;
END;

--You need to put multiple variables in a Record object, ditto
DECLARE
V_empno number (4);
My_row Emp%rowtype;
BEGIN
V_empno: = 7566;
SELECT * into My_row from emp WHERE empno=v_empno;
Dbms_output.put_line (my_row.ename| | ', ' | | My_row.sal);
END;

--Sometimes you don't need an entire column, only a few columns. Now with the record
DECLARE
--Custom Composite type My_emp
TYPE My_emp_type is RECORD (
Yg_name Emp.ename%type,
Yg_sal Emp.sal%type
);
My_row My_emp_type; --Variable name data type
BEGIN
SELECT ename,sal to My_row from EMP WHERE empno=7788;
Dbms_output.put_line (my_row.yg_name| | ', ' | | My_row.yg_sal);
END;

--Extension: Oracle does not have a Boolean type?
--thinking: Sex true= male, false= female. Disadvantages? Gender = confidentiality. So Oracle builds with char (1) instead, 1 = male 2= female 3 = confidential 4 = Shemale

The various collection types of--oracle, corresponding to the Java array.
--Reference variable: Explain the stored procedure later.

--binding variable (executed in command window, binding variable used:)
sql> var name varchar2 (10)
sql> execute:name: = ' Hello ';
PL/SQL procedure successfully completed
Name
---------
Hello

sql> Print name;
Name
---------
Hello

Oracle Definition Variables Summary