JDBC if a string exist in a database - sql

Question

I am trying to find where a specific string exist in a database (all tables). I have the following code:
DatabaseMetaData md = con.getMetaData();
ResultSet rs = md.getTables(null, null, "%", null);
while (rs.next()) {
stm = con.createStatement();
String sql;
sql = "SELECT * FROM "+rs.getString(3)+"WHERE F01 = '0000000000998'";
rs2 = stm.executeQuery(sql);
while(rs2.next()){
System.out.println(rs.getString(3));
}
}
The problem is in some of the tables F01 doesn't exist, so it throws an exception. Is there any way that even without specifying the column I can search through the whole table?

Answer 1

which database you are using.
Look over this discussion post. you may get good ideas about how to make sure column exists before you call your check
http://www.coderanch.com/t/299298/JDBC/databases/Oracle-describe-table-jdbc
For oracle
you can check these queries
select COLUMN_NAME, DATA_LENGTH, DATA_TYPE from user_tab_columns where Lower(table_name) = 'product'
select table_name, COLUMN_NAME, DATA_LENGTH, DATA_TYPE from user_tab_columns where upper(column_name) = 'PRODUCTID'
therefore your call should be something like this
select table_name from user_tab_columns where upper(column_name) = 'F01'
and then
SELECT * FROM "+rs.getString(1)+"WHERE F01 = '0000000000998'
as you see I am using LOWER and UPPER, you need to make sure you include them, reason as you can understand even though SQL is not case sensitive in its statements, but the value for which conditional check is happening is case sensitive.

Answer 2

The following Java code loops through each VARCHAR/NVARCHAR column in each table and performs a SELECT TOP 1 on that column to see if it gets a hit:
import java.sql.*;
import java.util.ArrayList;
import java.util.List;
public class JDBCQuery {
public static void main(String args[]) {
String textToSearchFor = "Gord"; // test data
System.out.println(String.format("The value '%s' was found in the following locations:", textToSearchFor));
Connection conn = null;
PreparedStatement ps = null;
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
String connectionString =
"jdbc:odbc:Driver={SQL Server};" +
"Server=.\\SQLEXPRESS;" +
"Trusted_Connection=yes;" +
"Database=myDb";
conn = DriverManager.getConnection(connectionString);
DatabaseMetaData md = conn.getMetaData();
ResultSet mdrs = md.getTables(null, null, "%", new String[] { "TABLE" });
List<String> tableList = new ArrayList<String>();
while (mdrs.next()) {
tableList.add(String.format("[%s].[%s].[%s]", mdrs.getString(1), mdrs.getString(2), mdrs.getString(3)));
// i.e., [catalogName].[schemaName].[tableName]
}
mdrs.close();
for (String tableName : tableList) {
Statement stmt = conn.createStatement();
stmt.execute("SELECT * FROM " + tableName + " WHERE 0=1");
ResultSet rs0 = stmt.getResultSet();
ResultSetMetaData rsmd = rs0.getMetaData();
List<String> columnList = new ArrayList<String>();
for (int colIndex = 1; colIndex <= rsmd.getColumnCount(); colIndex++) {
switch (rsmd.getColumnType(colIndex)) {
case java.sql.Types.VARCHAR:
case java.sql.Types.NVARCHAR:
columnList.add("[" + rsmd.getColumnName(colIndex) + "]");
break;
}
}
rs0.close();
stmt.close();
for (String columnName : columnList) {
String psSql = String.format("SELECT TOP 1 * FROM %s WHERE %s = ?", tableName, columnName);
ps = conn.prepareStatement(psSql);
ps.setString(1, textToSearchFor);
ResultSet rs1 = ps.executeQuery();
if (rs1.next()) {
System.out.println(String.format("column %s in %s", columnName, tableName));
}
rs1.close();
ps.close();
}
}
} catch( Exception e ) {
e.printStackTrace();
} finally {
try {
if (ps != null) {
ps.close();
}
if (conn != null) {
conn.close();
}
} catch( Exception e ) {
e.printStackTrace();
}
}
}
}
The results look like this;
The value 'Gord' was found in the following locations:
column [textCol] in [myDb].[dbo].[linkedTable]
column [FirstName] in [myDb].[dbo].[myContacts]