Working with tables
124
Altering tables in
Sybase Central
The property sheets for tables and columns display all the table or column
attributes. You can alter a table definition in Sybase Central by displaying the
property sheet for the table or column you wish to change, altering the property,
and clicking OK to commit the change.
Altering tables in a
join index
You cannot
ADD
,
DROP
or
MODIFY
a base table column that participates in a
join condition of a join index. To alter joined columns, you must first drop the
join index, alter the table, and then recreate the join index. See “Using join
indexes” for complete information on join indexes.
Dropping tables
The following
DROP TABLE
statement deletes all the records in the
skill
table
and then removes the definition of the
skill
table from the database
DROP TABLE skill
Like the
CREATE
statement, the
DROP
statement automatically executes a
COMMIT
before and after dropping the table. This makes permanent all
changes to the database since the last
COMMIT
or
ROLLBACK
.
The
DROP
statement also drops all indexes on the table, except if any column
in the table participates in a join index.
If you only want to remove data rows but not the table itself, use the
TRUNCATE TABLE
statement. If you truncate a table while other users are
reading from it, the normal rules of table versioning apply, that is, old table
versions remain until readers' transactions complete; see Chapter 8,
“Transactions and Versioning” for details.
DROP TABLE
and
TRUNCATE TABLE
are very fast, taking only seconds to
occur. The size of the data does not effect the speed of the operation.
For a full description of the
DROP
statement, see Adaptive Server IQ Reference
Manual.
❖
To drop a table in Sybase Central:
1
Connect to the database.
2
Click the Tables folder for that database.
3
Right-click the table you wish to delete, and select Delete from the pop-up
menu.
Summary of Contents for Adaptive Server IQ 12.4.2
Page 1: ...Administration and Performance Guide Adaptive Server IQ 12 4 2 ...
Page 16: ...xvi ...
Page 20: ...Related documents xx ...
Page 40: ...Compatibility with earlier versions 20 ...
Page 118: ...Troubleshooting startup shutdown and connections 98 ...
Page 248: ...Importing data by replication 228 ...
Page 306: ...Integrity rules in the system tables 286 ...
Page 334: ...Cursors in transactions 314 ...
Page 396: ...Users and permissions in the system tables 376 ...
Page 438: ...Determining your data backup and recovery strategy 418 ...
Page 484: ...Network performance 464 ...
Page 500: ...System utilities to monitor CPU use 480 ...
Page 514: ...Characteristics of Open Client and jConnect connections 494 ...
Page 536: ...Index 516 ...