Oracle Defaults one place to note __oracle

Take the character type as an example

Java code

public static void Main (string[] args) throws Exception {
      String sql = ' Select column_name, data_type, Data_default fr Om user_tab_columns WHERE table_name = ' TEST ';
      Connection con = drivermanager.getconnection (constr, username, password);
      ResultSet rs = con.createstatement (). executequery (SQL);
      while (Rs.next ()) {
         System.out.println (rs.getstring (1) + "T" + rs.getstring (2) + "\t|" + rs.getstring (3) + "|");
      }
      Rs.close ();
      Con.close ();
   }

Results

SQL statement	Java results	Note
CREATE TABLE Test (a VARCHAR2 (a) Default ' abc ');	A VARCHAR2 | ' ABC ' |	Normal, default value single quotes with parentheses behind
ALTER TABLE test Modify a default ' ABC ';	A VARCHAR2 | ' abc |	Line breaks appear after default values
ALTER TABLE test Modify a default ' abc ' NOT NULL;	A VARCHAR2 | ' ABC ' |	There are two spaces between ' abc ' and NOT NULL, and two spaces in Java results
ALTER TABLE test Modify a default 132 null;	A VARCHAR2 |132 |	Three spaces
ALTER TABLE test Modify a default 132/*dd*/NOT null;	A VARCHAR2 |132/*dd*/|	Add a note to the situation
ALTER TABLE test Modify a default ' abc '/*dd*/;	A VARCHAR2 | ' ABC '/*dd*/ |	Comments, wrapping
ALTER TABLE test Modify a default ' abc ' NULL/*dd*/;	A VARCHAR2 | ' ABC ' |

The result of the above is only to show that there is a problem, when inserting data, the default value is still 132 or ABC, there will be no space, wrapping, note the case. Similar situations can occur with other types of fields

ALTER TABLE Test add b number default/*dd*/;
ALTER TABLE test add c date default sysdate/*dd*/;

Sql> desc Test
Name Type         Nullable Default        Comments 
-------------------------------------------- -- 
A    VARCHAR2 (A) y        123/*dd*/B number       y        /*dd*/               
C    DATE         y