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[英]How can I list database tables in a set of databases using the new DBCPConnectionPoolLookup in NiFi?
[英]How do I list multiple databases with their tables by using “Show Tables” via Java?
我试图用Java列出MySQL数据库及其表。 现在,我有两个数据库,分别是“带有MySQL_Database_Service的 Database_Services , MSSQL_Database_Service和带有Active_Directory的 Directory_Services , OpenLDAP表。我获得了Database_Services及其表的输出,但是没有得到其他数据库 。
public class connectMySQL implements serverConnection{
Connection conn;
Statement stmt;
public void connect(String dbName){
String url;
try {
if(dbName.equals("")){
url = "jdbc:mysql://x:x/";
}
else{
url = "jdbc:mysql://x:x”+ dbName;
}
String username = “x”;
String password = "x";
conn = DriverManager.getConnection(url,username,password);
stmt = conn.createStatement();
}
catch (SQLException ex)
{
System.out.println("An error occurred. Maybe user/password is invalid");
ex.printStackTrace();
}
}
}
public class listInf extends connectMySQL implements listInfrastructure {
public void list() {
String dbName;
ResultSet rs;
try{
connect("");
String str = "SHOW DATABASES";
ResultSet resultSet = stmt.executeQuery(str);
while(resultSet.next()){
dbName = resultSet.getString("Database");
if(!dbName.contains("schema") && !dbName.equals("mysql")){
System.out.println(dbName);
rs = stmt.executeQuery("SHOW TABLES IN " + dbName);
while (rs.next()) {
System.out.println("\t" + rs.getString("Tables_in_" + dbName));
}
}
}
}
catch(SQLException e){
System.out.println("Error");
}
}
}
我想得到类似的输出:
Database_Services:
Directory_Services:
Active_Directory_Service。
OpenLDAP_Service。
Connection conn1 = DriverManager.getConnection(url, username, password);
Connection conn2 = DriverManager.getConnection(url, username, password);
Statement statement1 = conn1.createStatement();
Statement statement2 = conn2.createStatement();
ResultSet resultSet1 = statement1.executeQuery("SHOW TABLES IN DB1");
ResultSet resultSet2 = statement2.executeQuery("SHOW TABLES IN DB2");
while (resultSet1.next()) {
System.out.println("");
}
while (resultSet2.next()) {
System.out.println("");
}
如果您有两个以上的数据库,则只需使用loop即可获取结果。
您可以使用元信息数据库information_schema
。
SELECT
TABLE_SCHEMA,
TABLE_NAME
FROM information_schema.TABLES
WHERE TABLE_SCHEMA IN ('Database_Services', 'Directory_Services')
ORDER BY TABLE_SCHEMA
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