Modify Multiple columns in table SyntaxTo MODIFY MULTIPLE COLUMNS in an existing table, the Oracle ALTER TABLE syntax is: ALTER TABLE tablenameMODIFY (column1 columntype,column2 columntype.columnn columntype); ExampleLet's look at an example that shows how to modify multiple columns in an Oracle table using the ALTER TABLE statement.For example: ALTER TABLE customersMODIFY (customername varchar2(100) NOT NULL,city varchar2(75) DEFAULT 'Seattle' NOT NULL);This Oracle ALTER TABLE example will modify both the customername and city columns. The customername column will be set to a varchar2(100) data type and not allow null values.
When i look at the columns they are defined as: Column1 Varchar2(35) Column2 Varchar2(40) When I am exporting the data set to a Fixed width file, I want to manually say that the length of the column1 is 40 bytes and length of column2 is 50 bytes etc. And not 35 or 40. Please Advise. TOAD allows you to change the data that appears in the Data tab of the results panel. The data columns being selected must include the ROWID column as well. Another way to select data from an object for update is by using edit syntax. It's probably possible to html-code a (right side) column border (in the email itself), and to set it at a specified width, send it to the receiver, to allow for re-adjusting at the receiver's end. (Maybe set/override these column contained emails, to a user's default, automatically.).
The city column will be set to a varchar2(75) data type, its default value will be set to 'Seattle', and the column will not allow null values. Rename column in table(NEW in Oracle 9i Release 2) SyntaxStarting in Oracle 9i Release 2, you can now rename a column.To RENAME A COLUMN in an existing table, the Oracle ALTER TABLE syntax is: ALTER TABLE tablenameRENAME COLUMN oldname TO newname; ExampleLet's look at an example that shows how to rename a column in an Oracle table using the ALTER TABLE statement.For example: ALTER TABLE customersRENAME COLUMN customername TO cname;This Oracle ALTER TABLE example will rename the column called customername to cname.
Practice Exercise #1:Based on the departments table below, rename the departments table to depts. CREATE TABLE departments( departmentid number(10) NOT NULL,departmentname varchar2(50) NOT NULL,CONSTRAINT departmentspk PRIMARY KEY (departmentid)); Solution for Practice Exercise #1:The following Oracle ALTER TABLE statement would rename the departments table to depts: ALTER TABLE departmentsRENAME TO depts; Practice Exercise #2:Based on the employees table below, add a column called bonus that is a number(6) datatype.
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CREATE TABLE employees( employeenumber number(10) NOT NULL,employeename varchar2(50) NOT NULL,departmentid number(10),CONSTRAINT employeespk PRIMARY KEY (employeenumber)); Solution for Practice Exercise #2:The following Oracle ALTER TABLE statement would add a bonus column to the employees table: ALTER TABLE employeesADD bonus number(6); Practice Exercise #3:Based on the customers table below, add two columns - one column called contactname that is a varchar2(50) datatype and one column called lastcontacted that is a date datatype. CREATE TABLE customers( customerid number(10) NOT NULL,customername varchar2(50) NOT NULL,address varchar2(50),city varchar2(50),state varchar2(25),zipcode varchar2(10),CONSTRAINT customerspk PRIMARY KEY (customerid)); Solution for Practice Exercise #3:The following Oracle ALTER TABLE statement would add the contactname and lastcontacted columns to the customers table: ALTER TABLE customersADD (contactname varchar2(50),lastcontacted date); Practice Exercise #4:Based on the employees table below, change the employeename column to a varchar2(75) datatype. CREATE TABLE employees( employeenumber number(10) NOT NULL,employeename varchar2(50) NOT NULL,departmentid number(10),CONSTRAINT employeespk PRIMARY KEY (employeenumber)); Solution for Practice Exercise #4:The following Oracle ALTER TABLE statement would change the datatype for the employeename column to varchar2(75): ALTER TABLE employeesMODIFY employeename varchar2(75); Practice Exercise #5:Based on the customers table below, change the customername column to NOT allow null values and change the state column to a varchar2(2) datatype. CREATE TABLE customers( customerid number(10) NOT NULL,customername varchar2(50),address varchar2(50),city varchar2(50),state varchar2(25),zipcode varchar2(10),CONSTRAINT customerspk PRIMARY KEY (customerid)); Solution for Practice Exercise #5:The following Oracle ALTER TABLE statement would modify the customername and state columns accordingly in the customers table: ALTER TABLE customersMODIFY (customername varchar2(50) NOT NULL,state varchar2(2)); Practice Exercise #6:Based on the employees table below, drop the salary column. CREATE TABLE employees( employeenumber number(10) NOT NULL,employeename varchar2(50) NOT NULL,departmentid number(10),salary number(6),CONSTRAINT employeespk PRIMARY KEY (employeenumber)); Solution for Practice Exercise #6:The following Oracle ALTER TABLE statement would drop the salary column from the employees table: ALTER TABLE employeesDROP COLUMN salary; Practice Exercise #7:Based on the departments table below, rename the departmentname column to deptname.
CREATE TABLE departments( departmentid number(10) NOT NULL,departmentname varchar2(50) NOT NULL,CONSTRAINT departmentspk PRIMARY KEY (departmentid)); Solution for Practice Exercise #7:The following Oracle ALTER TABLE statement would rename the departmentname column to deptname in the departments table: ALTER TABLE departmentsRENAME COLUMN departmentname TO deptname.