I'm using the below code to load tables from Access queries. It gives the sqlldr error so I printed the query string like shown below and found the order of the columns in the SELECT statement is not the same as in the query in the Access database. I'm very baffled by this. Has someone experienced the same thing?
sourceConn =
(UcanaccessConnection)DriverManager.getConnection("jdbc:ucanaccess://"
+ path);
List<Query> queries = sourceConn.getDbIO().getQueries();
for(Query query : queries) {
queryStr = query.toSQLString();
System.out.println("Query to process: " + queryStr);
}
Related
I am using Telerik Data Access to perform OR mapping.
I am trying to use Linq for performing a join query but not sure how to proceed correctly.
The original sql query is given by:
'SELECT O.OPS_LEG_ID, O.ATD_DATE, O.DEP_AIRPORT_ACT, O.ARR_AIRPORT_ACT, O.ATA_DATE, '+
'O.FL_LOG_ATD_DATE, O.FL_LOG_ATA_DATE, O.FL_LOG_DEP_AIRPORT, O.FL_LOG_ARR_AIRPORT, '+
'O.FL_NB, O.DESIGNATOR, O.FL_LOG_ID, O.FL_LOG_STATUS '+
'FROM CREW_ROT_ROLE CR, OPS_LEG O, CREW_ROLES R, CREW_PAIRING_CMP CP '+
'WHERE CR.ROLE_CDE = R.ROLE_CDE '+
'AND CR.CREW_ROTATION_ID = CP.CREW_ROTATION_ID '+
'AND CP.OPS_LEG_ID = O.OPS_LEG_ID '+
'AND CR.CREW_CDE = :CREW_CDE '+
'AND O.ATD_DATE >= :D_FROM '+
'AND O.ATD_DATE <= :D_TO '+
//'AND R.ROLE_TYPE = 0 '+
'ORDER BY O.ATD_DATE
The corresponding Entities have been generated from the SQL tables. I am now trying to build the equivalent Linq query, which does not seem to work:
var results = from opsLeg in dbContext.OPS_LEGs
from crewRotationRole in dbContext.CREW_ROT_ROLEs
from crewRole in dbContext.CREW_ROLEs
from crewPairingComponent in dbContext.CREW_PAIRING_CMPs
where crewRotationRole.ROLE_CDE == crewRole.ROLE_CDE
&& crewRotationRole.CREW_ROTATION_ID == crewPairingComponent.CREW_ROTATION_ID
&& crewPairingComponent.OPS_LEG_ID == opsLeg.OPS_LEG_ID
&& crewRotationRole.CREW_CDE == userId
select new { OpsLegId = opsLeg.OPS_LEG_ID,
Designator = opsLeg.DESIGNATOR,
FlightNumber = opsLeg.FL_NB
};
Trying the previous query, raises an exception:
"Identifier 'ROLE_CDE' is not a parameter or variable or field of
'FlightLogEntities.OPS_LEG'. If 'ROLE_CDE' is a property please add
the FieldAlias or Storage attribute to it or declare it as a field's
alias."
Not sure how to proceed. What would be the correct query using Linq joins? Thanks!
If you are using a ORM like Entity framework, then the conceptual model would be mix of classes, which would provide a object centric view of data.
So, you would be using the Linq on Objects and in that case you need not write queries for joins as we do in SQL for a database. Conceptual model would contain objects which would be having relationships using navigational properties, and to access navigational properties you can access them as a property of object.
For e.g if there are 2 tables in Database, Customer & Orders. Following SQL statement will return all Orders for Customer number 1:
SELECT Customers.CustomerName, Orders.OrderID
FROM Customers
INNER JOIN Orders
ON Customers.CustomerID=Orders.CustomerID
Where Customers.CustomerID = 1
If we use the EF to generate to generate the conceptual model from Database, we would get class for Customer and Order and Customer class would have a property of ICollection. So, if you need the same results as the SQL query above, you would do it in following way
var CustomerOne = context.Customers.Where(x => x.CustomerID == 1);
var ordersForCustomerOne = CustomerOne.Orders;
You can try something like
var k = from r in dataContext.Order_Details
join t in dataContext.Orders on r.OrderID equals t.OrderID
select r.OrderID ;
I've got a table in my Google Cloud SQL database with an auto-incrementing column.
How do I execute an INSERT query via google-apps-script/JDBC and get back the value for the newly incremented column?
For example, my column is named ticket_id. I want to INSERT and have the new ticket_id value be returned in the result set.
In other words, if I have the following structure, what would I need to modify or how, so that I can do something like rs = stmt.getGeneratedKeys();
var conn = Jdbc.getCloudSqlConnection("jdbc:google:rdbms:.......
var stmt = conn.createStatement();
//build my INSERT sql statement
var sql = "insert into ......
var rs = stmt.executeUpdate(sql);
I see that there is a JDBC statement class with a member called RETURN_GENERATED_KEYS but I have so far not been smart enough to figure out how to properly manipulate that and get what I need. Is RETURN_GENERATED_KEYS a constant, is it an attribute, or how can I make use of it?
It seems like the documentation with the Apps Script JDBC service is a bit lacking. I've created an internal task item for that. Thankfully, Apps Script JDBC API follows the Java JDBC API pretty closely. The key is to get the result set back using the stmt.getGeneratedKeys() call.
I built a sample table using the animals example from the MySQL docs and this sample below works nicely against that and logs the next incremented ID.
function foo() {
var conn = Jdbc.getCloudSqlConnection("jdbc:google:rdbms://<instance>/<db>");
var stmt = conn.createStatement();
var sql = "INSERT INTO animals (name) VALUES ('dog')";
var count = stmt.executeUpdate(sql,1)//pass in any int for auto inc IDs back
var rs = stmt.getGeneratedKeys();
//if you are only expecting one row back, no need for while loop
// just do rs.next();
while(rs.next()) {
Logger.log(rs.getString(1));
}
rs.close();
stmt.close();
conn.close();
}
Is there any Inbuilt function in Linq to Print the month Name while working with LINQPAD?
I want to print the month name in the following Scenario
var query = from e in Employees
let month=e.BirthDate.GetValueOrDefault()
let birthmonth=month.ToString("MMMM")
select birthmonth;
query.Dump();
When I run this it is throwing NotSupportedException.
how to print the month name in Linq to Sql?
Rather than using ToString, try string.Format. Something like:
var query = (from e in Employees
let month = e.BirthDate.GetValueOrDefault()
let birthmonth = string.Format("{0:MMMM}", month)
select birthmonth);
query.Dump();
This seems to work from my local testing, although it is not included as part of the SQL query.
Do it in two steps, one to get the months from the database, then another using Linq-To-Objects to perform the formatting.
var birthDates = Employees.Select(e => e.BirthDate).ToList();
var query = birthDates.Select(d => d != null ? d.ToString("MMMM") : "Null");
query.Dump();
Whatever ORM you are using can't convert the string formatting part of you query into SQL that works on your database. So, doing it in two steps and using ToList to evaluate inbetween overcomes that problem.
I need to enumerate the tables in a Derby (aka Java DB) database using JDBC in a Java program. All I am aware of for doing this is the SHOW TABLES command.
I first tried with something similar to this...
String strConnectionURL = "jdbc:derby:/path/to/derby/database;create=false";
Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
Connection connection = DriverManager.getConnection(strConnectionURL);
Statement statement = connection.createStatement();
boolean boResult = statement.execute("SHOW TABLES");
if (boResult) {
System.out.println("yay!");
}
...but that throws an exception:
java.sql.SQLSyntaxErrorException: Syntax error: Encountered "SHOW" at line 1, column 1.
So next I thought maybe I needed to use a CallableStatement so I tried this...
String strConnectionURL = "jdbc:derby:/path/to/derby/db;create=false";
Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
Connection connection = DriverManager.getConnection(strConnectionURL);
CallableStatement statement = connection.prepareCall("SHOW TABLES");
boolean boResult = statement.execute();
if (boResult) {
System.out.println("yippee!");
}
...but that throws the same exception:
java.sql.SQLSyntaxErrorException: Syntax error: Encountered "SHOW" at line 1, column 1.
So, can anyone help me enumerate the tables in my Derby (Java DB) database from JDBC?
EDIT: I'm looking around and starting to get a feeling this may be a general JDBC question. In other words, one could/would enumerate all a db's tables with the DatabaseMetaData object that can be retrieved from the Connection object. Looking into that (and looking forward to responses)...
EDIT 2: I found a pure JDBC solution, but am still happy to hear alternatives...
String strConnectionURL = "jdbc:derby:/path/to/db;create=false";
Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
Connection connection = DriverManager.getConnection(strConnectionURL);
DatabaseMetaData dbmd = connection.getMetaData();
ResultSet resultSet = dbmd.getTables(null, null, null, null);
while (resultSet.next()) {
String strTableName = resultSet.getString("TABLE_NAME");
System.out.println("TABLE_NAME is " + strTableName);
}
Show Tables is an ij command, not a base SQL statement, so you can't directly execute it. As you noted in your "EDIT 2", you can use the DatabaseMetaData to do this. Two other ways to do it are: you can select from the system catalogs (see http://db.apache.org/derby/docs/10.8/ref/rrefsistabs24269.html) , or you can use the "ij.runScript" method to run the ij tool from within your program, and pass it the "show tables" command (see http://db.apache.org/derby/docs/10.8/publishedapi/jdbc3/org/apache/derby/tools/ij.html)
As Bryan suggested ij.runScript - the code would look like this:
public void showTbls() throws Exception{
String sqlIn = "SHOW TABLES;";
InputStream stream = new ByteArrayInputStream(sqlIn.getBytes(StandardCharsets.UTF_8));
ij.runScript(conn,stream,StandardCharsets.UTF_8.name(), System.out,"UTF-8");
stream.close();
}
assumming conn is a opened derby Connection
But the disadvantage is that you are getting only string output. Not an ResultSet as you would get from:
Statement stmt = conn.createStatement();
ResultSet results = stmt.executeQuery("SELECT * FROM sys.systables");
or if you want only user table names you can use following SQL:
ResultSet results = stmt.executeQuery("SELECT TABLENAME FROM SYS.SYSTABLES WHERE TABLETYPE='T'");
A very similar output to
SHOW TABLES;
can be produced by using the following jdbc compliant query:
SELECT TABLENAME, (SELECT SCHEMANAME
FROM SYS.SYSSCHEMAS
WHERE SYS.SYSTABLES.SCHEMAID = SYS.SYSSCHEMAS.SCHEMAID)
AS SCHEMANAME
FROM SYS.SYSTABLES WHERE TABLETYPE='T'
It also shows you the probably useful SCHEMA information for each TABLE entry. Skip
TABLETYPE='T'
if you also want to see the system tables of your database as the user before has mentioned already.
My current project is to take information from an OleDbDatabase and .CSV files and place it all into a larger OleDbDatabase.
I have currently read in all the information I need from both .CSV files, and the OleDbDatabase into DataTables.... Where it is getting hairy is writing all of the information back to another OleDbDatabase.
Right now my current method is to do something like this:
OleDbTransaction myTransaction = null;
try
{
OleDbConnection conn = new OleDbConnection("PROVIDER=Microsoft.Jet.OLEDB.4.0;" +
"Data Source=" + Database);
conn.Open();
OleDbCommand command = conn.CreateCommand();
string strSQL;
command.Transaction = myTransaction;
strSQL = "Insert into TABLE " +
"(FirstName, LastName) values ('" +
FirstName + "', '" + LastName + "')";
command.CommandType = CommandType.Text;
command.CommandText = strSQL;
command.ExecuteNonQuery();
conn.close();
catch (Exception)
{
// IF invalid data is entered, rolls back the database
myTransaction.Rollback();
}
Of course, this is very basic and I'm using an SQL command to commit my transactions to a connection. My problem is I could do this, but I have about 200 fields that need inserted over several tables. I'm willing to do the leg work if that's the only way to go. But I feel like there is an easier method. Is there anything in LINQ that could help me out with this?
If the column names in the DataTable match exactly to the column names in the destination table, then you might be able to use a OleDbCommandBuilder (Warning: I haven't tested this yet). One area you may run into problems is if the data types of the source data table do not match those of the destination table (e.g if the source column data types are all strings).
EDIT
I revised my original code in a number of ways. First, I switched to using the Merge method on a DataTable. This allowed me to skip using the LoadDataRow in a loop.
using ( var conn = new OleDbConnection( destinationConnString ) )
{
//query off the destination table. Could also use Select Col1, Col2..
//if you were not going to insert into all columns.
const string selectSql = "Select * From [DestinationTable]";
using ( var adapter = new OleDbDataAdapter( selectSql, conn ) )
{
using ( var builder = new OleDbCommandBuilder( adapter ) )
{
conn.Open();
var destinationTable = new DataTable();
adapter.Fill( destinationTable );
//if the column names do not match exactly, then they
//will be skipped
destinationTable.Merge( sourceDataTable, true, MissingSchemaAction.Ignore );
//ensure that all rows are marked as Added.
destinationTable.AcceptChanges();
foreach ( DataRow row in destinationTable.Rows )
row.SetAdded();
builder.QuotePrefix = "[";
builder.QuoteSuffix= "]";
//forces the builder to rebuild its insert command
builder.GetInsertCommand();
adapter.Update( destinationTable );
}
}
}
ADDITION An alternate solution would be to use a framework like FileHelpers to read the CSV file and post it into your database. It does have an OleDbStorage DataLink for posting into OleDb sources. See the SqlServerStorage InsertRecord example to see how (in the end substitute OleDbStorage for SqlServerStorage).
It sounds like you have many .mdb and .csv that you need to merge into a single .mdb. This answer is running with that assumption, and that you have SQL Server available to you. If you don't, then consider downloading SQL Express.
Use SQL Server to act as the broker between your multiple datasources and your target datastore. Script each datasource as an insert into a SQL Server holding table. When all data is loaded into the holding table, perform a final push into your target Access datastore.
Consider these steps:
In SQL Server, create a holding table for the imported CSV data.
CREATE TABLE CsvImport
(CustomerID smallint,
LastName varchar(40),
BirthDate smalldatetime)
Create a stored proc whose job will be to read a given CSV filepath, and insert into a SQL Server table.
CREATE PROC ReadFromCSV
#CsvFilePath varchar(1000)
AS
BULK
INSERT CsvImport
FROM #CsvFilePath --'c:\some.csv'
WITH
(
FIELDTERMINATOR = ',', --your own specific terminators should go here
ROWTERMINATOR = '\n'
)
GO
Create a script to call this stored proc for each .csv file you have on disk. Perhaps some Excel trickery or filesystem dir piped commands can help you create these statements.
exec ReadFromCSV 'c:\1.csv
For each .mdb datasource, create a temp linked server.
DECLARE #MdbFilePath varchar(1000);
SELECT #MdbFilePath = 'C:\MyMdb1.mdb';
EXEC master.dbo.sp_addlinkedserver #server = N'MY_ACCESS_DB_', #srvproduct=N'Access', #provider=N'Microsoft.Jet.OLEDB.4.0', #datasrc=#MdbFilePath
-- grab the relevant data
--your data's now in the table...
INSERT CsvImport(CustomerID,
SELECT [CustomerID]
,[LastName]
,[BirthDate]
FROM [MY_ACCESS_DB_]...[Customers]
--remove the linked server
EXEC master.dbo.sp_dropserver #server=N'MY_ACCESS_DB_', #droplogins='droplogins'
When you're done importing data into that holding table, create a Linked Server in your SQL Server instance. This is the target datastore. SELECT the data from SQL Server into Access.
EXEC master.dbo.sp_addlinkedserver #server = N'MY_ACCESS_TARGET', #srvproduct=N'Access', #provider=N'Microsoft.Jet.OLEDB.4.0', #datasrc='C:\Target.mdb'
INSERT INTO [MY_ACCESS_TARGET]...[Customer]
([CustomerID]
,[LastName]
,[BirthDate])
SELECT Customer,
LastName,
BirthDate
FROM CsvImport