Listing Tables and Databases

9.10.1 Problem

You want a list of tables in a database or a list of databases hosted by the MySQL server.

9.10.2 Solution

Use SHOW TABLES or SHOW DATABASES.

9.10.3 Discussion

To obtain a list of tables in the current database, use this query:

SHOW TABLES;

However, if no database has been selected, the query will fail. To avoid this problem, you should either make sure there is a current database or name a database explicitly:

SHOW TABLES FROM db_name;

Another form of SHOW returns a list of databases hosted by the server:

SHOW DATABASES;

Be Careful with SHOW Statements

Be careful how you interpret the results from SHOW TABLES and SHOW DATABASES. The result from SHOW TABLES will be empty if you don't have permission to access the table. The result from SHOW DATABASES may be empty as well. If the server was started with the --safe-show-database or --skip-show-database option, you may not be able to get much information with the SHOW DATABASES statement.

If you're looking for a database-independent way to get table or database lists and you're using Perl or Java, try the following methods.

In Perl, DBI provides a tables( ) function that returns a list of tables. It works for the current database only:

my @tables = $dbh->tables ( );

In Java, you can use JDBC methods designed to return lists of tables or databases. For each method, invoke your connection object's getMetaData( ) method and use the resulting DatabaseMetaData object to retrieve the information you want. Here's how to list the tables in a given database:

// get list of tables in database named by dbName; if
// dbName is the empty string, the current database is used
DatabaseMetaData md = conn.getMetaData ( );
ResultSet rs = md.getTables (dbName, "", "%", null);
while (rs.next ( ))
 System.out.println (rs.getString (3)); // column 3 = table name
rs.close ( );

A similar procedure produces a list of databases:

// get list of databases
DatabaseMetaData md = conn.getMetaData ( );
ResultSet rs = md.getCatalogs ( );
while (rs.next ( ))
 System.out.println (rs.getString (1)); // column 1 = database name
rs.close ( );

Using the mysql Client Program

Writing MySQL-Based Programs

Record Selection Techniques

Working with Strings

Working with Dates and Times

Sorting Query Results

Generating Summaries

Modifying Tables with ALTER TABLE

Obtaining and Using Metadata

Importing and Exporting Data

Generating and Using Sequences

Using Multiple Tables

Statistical Techniques

Handling Duplicates

Performing Transactions

Introduction to MySQL on the Web

Incorporating Query Resultsinto Web Pages

Processing Web Input with MySQL

Using MySQL-Based Web Session Management

Appendix A. Obtaining MySQL Software

Appendix B. JSP and Tomcat Primer

Appendix C. References



MySQL Cookbook
MySQL Cookbook
ISBN: 059652708X
EAN: 2147483647
Year: 2005
Pages: 412
Authors: Paul DuBois

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