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4.2.2.3.7: IBM extensions to JSP syntax >
4.2.2.3.7.2: JSP syntax: Tags for database access
4.2.2.3.7.2: JSP syntax: Tags for database access
Beginning with IBM WebSphere Application Server Version 3.x, the JSP 1.0 support
was extended to provide syntax
for database access. The syntax makes it simple to add a database connection
to a Web page and then use that connection to query or update the database.
The user ID and password for the database connection can be provided by the
user at request-time or hard coded within the JSP file.
The table summarizes the tags. Click a tag to link to its syntax description.
Goal |
Tag |
Details and examples |
Specify information needed to make a connection to a JDBC or an ODBC database. |
<tsx:dbconnect> |
The <tsx:dbconnect> syntax does not establish the connection. Instead,
the <tsx:dbquery> and <tsx:dbmodify> syntax are used to reference
a <tsx:dbconnect> in the same JSP file and establish the connection.
When the JSP file is compiled into a servlet, the Java processor adds
the Java coding for the <tsx:dbconnect> syntax to the servlet's
service() method, which means a new database connection is created for each
request for the JSP file.
|
Avoid hard coding the user ID and password in the
<tsx:dbconnect>. |
<tsx:userid> and <tsx:passwd> |
Use the <tsx:userid> and <tsx:passwd> to accept
user input for the values and then add that data to the request object. The request object
can be accessed by a JSP file (such as the JSPEmployee.jsp example) that requests the database
connection.
The <tsx:userid> and <tsx:passwd> must be used within a
<tsx:dbconnect> tag.
|
Establish a connection to a database, submit database queries, and return the results set. |
<tsx:dbquery> |
The <tsx:dbquery>:
- References a <tsx:dbconnect> in the same JSP file and uses the information it provides to determine the database URL and driver. The user ID and password are also obtained from the <tsx:dbconnect> if those values are provided in the <tsx:dbconnect>.
- Establishes a new connection
- Retrieves and caches data in the results object
- Closes the connection (releases the connection resource)
|
Establish a connection to a database and then add records to a database table. |
<tsx:dbmodify> |
The <tsx:dbmodify>:
- References a <tsx:dbconnect> in the same JSP file and uses the information provided by that to determine the database URL and driver. The user ID and password are also obtained from the <tsx:dbconnect> if those values are provided in the <tsx:dbconnect>.
- Establishes a new connection
- Updates a table in the database
- Closes the connection (releases the connection resource)
Examples:
Basic example
|
Display query results. |
<tsx:repeat> and <tsx:getProperty> |
The <tsx:repeat> loops through each of the rows in the query results.
The <tsx:getProperty> uses the query results object (for the <tsx:dbquery>
syntax whose identifier is specified by the <tsx:getProperty> bean attribute)
and the appropriate column name (specified by the <tsx:getProperty> property
attribute) to retrieve the value.
Note: You cannot assign the value from the <tsx:getProperty> tag to
a variable. The value, generated as output from this tag, is displayed in the Browser window.
Examples:
Basic example |
|
|