Sqlplus Study Notes (1)

Sqlplus learning notes (1) create a table and insert data [SQL] create table user_emp (id number (4), passwd char (4), name char (20 ), phone char (20), email varchar2 (50); prompt Table Created indicates that the Table has been successfully Created> data type <> number (n) number (n digits at most) number (n, m) floating point number (n digits in total, m digits after the decimal point) for example: number (7, 2) indicates the maximum number of 99999.99 <> string char (n) it indicates that a fixed-length string (easy to query) can be up to n characters long. If the entered data is not n characters long enough, there will be no space. In any case, it will take up to n characters long. Varchar (n) indicates that a variable-length string can be up to n characters. when the data is put into a variable-length string, the length of the variable occupies a large space varchar2 (n) oracle custom variable-length string <> the date inserts user data into the data table [SQL] insert into user_emp values (1001, '20140901', 'libuse', '20160301 ', 'lius @ 163.com '); the characters in the database are enclosed in single quotes, and numbers are not required. Data Query [SQL] select * from user_emp; three SQL statements summary <1> create a table name (column name type ,...) <2> insert data into table name values (column value ,...) <3> query the select * from table name;