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18.3 Some JDBC Utilities

473

18.3 Some JDBC Utilities

In many applications, you don't need to process query results a row at a time.

For example, in servlets and JSP pages, it is common to simply format the

database results (treating all values as strings) and present them to the user in

an HTML table (see Sections 18.4 and 18.8), in an Excel spreadsheet (see

Section 11.2), or distributed throughout the page. In such a case, it simplifies

processing to have methods that retrieve and store an entire 

ResultSet

 for

later display. 

This section presents two classes that provide this basic functionality along

with a few formatting, display, and table creation utilities. The core class is

DatabaseUtilities

, which implements static methods for four common

tasks:

1.

getQueryResults

This method connects to a database, executes a query, retrieves 

all the rows as arrays of strings, and puts them inside a 

DBResults

 object (see Listing 18.7). This method also places 

the database product name, database version, the names of all 

the columns and the 

Connection

 object into the 

DBResults

object. There are two versions of 

getQueryResults

: one that 

makes a new connection and another that uses an existing con 

nection.

2.

createTable

Given a table name, a string denoting the column formats, and 

an array of strings denoting the row values, this method con 

nects to a database, removes any existing versions of the desig 

nated table, issues a 

CREATE TABLE

 command with the 

designated format, then sends a series of 

INSERT INTO

 com 

mands for each of the rows. Again, there are two versions: one 

that makes a new connection and another that uses an existing 

connection. 

3.

printTable

Given a table name, this method connects to the specified data 

base, retrieves all the rows, and prints them on the standard 

output. It retrieves the results by turning the table name into a 

query of the form  

SELECT * FROM tableName

  and passing it 

to 

getQueryResults

.

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