CODEWITHSUNDEEP
javajdbc
zaib7777
zaib7777

Reputation: 89

Checking if a table is present in database

I have a list called tList, which contains names of tables of a database. Tables in this list may or may not exist. I want to retrieve data from every table if it is present. I am doing it like this.

for(String t:tList){
    sql=Select * from t
}

But in this scenario if table is not present, I am getting exception that table is not present and my program gets terminate. How to handle this so that I can retrieve data only and only if that table is present

In one more scenario if table is present but it is empty than also I am getting error. Please help in these two scenarios

Upvotes: 1

Views: 266

Answers (2)

Optional
Optional

Reputation: 4507

Have you tried DatabaseMetaData.getTables() Example:

DatabaseMetaData md = connection.getMetaData();
ResultSet rs = md.getTables(null, null, t, null); //t is your tableName (defined in loop of your question)
while (rs.next()) {
  System.out.println(rs.getString(3));
}

Edit

To answer your empty table question:

  //your query
  sql=Select * from t
  Statement  stmt = yourDBConnection.createStatement();
  ResultSet rs = stmt.executeQuery(sql);
  if (!rs .isBeforeFirst() ) {    
   System.out.println("Table is empty"); 
  }

Upvotes: 1

Jaydeep Rajput
Jaydeep Rajput

Reputation: 3673

I think the more appropriate way is to get data is java.sql.DataBaseMetaData.

A java.sql.Connection object is able to provide information describing its tables, its supported SQL grammar, its stored procedures, the capabilities of this connection, and so on. This information is obtained with the getMetaData method.

Refer: https://docs.oracle.com/javase/7/docs/api/java/sql/Connection.html https://docs.oracle.com/javase/7/docs/api/java/sql/DatabaseMetaData.html

Upvotes: 1

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