query for tables

Hello

In my computer, I have some databases for different applications. I want to check a database to see whether it has tables that I need or not. If there are needed tables, I will create a connect to that database. If not, no connection is created.

How I can do that

Thanks

[301 byte] By [suhua] at [2007-11-27 9:42:20]

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# 1

> I want to check a database to see whether it has tables that I need or not. If there> are needed tables, I will create a connect to that database. If not, no connection is created.do you already know how to connect to a specific database?

Yannixa at 2007-7-12 23:45:34 >

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# 2

Yep, I know. What I want is when user enter a wrong database name (but this database is already existed in the system - but with different data), that user cannot create a connection (or error is displayed)

suhua at 2007-7-12 23:45:34 >

# 3

You cannot query a database without connecting to it.Just connect to it, check if it has the tables, if not then simply close the connection and show a warning or so.

BalusCa at 2007-7-12 23:45:34 >

# 4

You need to connect to the database in order to find whether that database has that table or not. How you can see if that db has desired table or not without even connecting to it.

sncmp3it2a at 2007-7-12 23:45:34 >

# 5

Yep, my main question is how I can know "whether a database has a needed table or not." ?

If I have query "SELECT * FROM my_table_name" for a connection to a database. It return null when that database does not have the table "my_table_name". But it also return null if that database has the table "my_table_name" and it is empty. How I can distinct two cases.

Thanks

suhua at 2007-7-12 23:45:34 >

# 6

Make use of the DatabaseMetaData, which is available by Connection#getMetaData(). The getCatalogs() function returns a resultset with the table names.You can also do it with SQL, but the specific queries differs per DB.

BalusCa at 2007-7-12 23:45:34 >

# 7

> Yep, my main question is how I can know "whether a

> database has a needed table or not." ?

> If I have query "SELECT * FROM my_table_name" for a

> connection to a database. It return null when that

> database does not have the table "my_table_name".

No. An SQLException will be thrown.

> But

> it also return null if that database has the table

> "my_table_name" and it is empty.

No. An empty ResultSet will be returned.

> How I can distinct

> two cases.

> Thanks

itupjalua at 2007-7-12 23:45:34 >

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