jdbc

问题 at work we have to deal with several MS Access mdb files, so we use the default JdbcOdbcBridge Driver which comes with the Sun JVM and, for most cases, it works great. The problem is that when we have to deal with some larger files, we face several times exceptions with the message "Can't open any more tables". How can we avoid that? We already close all our instances of PreparedStatements and RecordSets, and even set their variables to null, but even so this exception continues to happen.

问题 at work we have to deal with several MS Access mdb files, so we use the default JdbcOdbcBridge Driver which comes with the Sun JVM and, for most cases, it works great. The problem is that when we have to deal with some larger files, we face several times exceptions with the message "Can't open any more tables". How can we avoid that? We already close all our instances of PreparedStatements and RecordSets, and even set their variables to null, but even so this exception continues to happen.

问题 Is there a way to cancel the copying process started by calling copyIn() method in a separate thread? Say, I have a list of csv-files which I need to copy from, getting maximum of database server power. So I create n-threads-connections for n-files, but I cannot find a way to abort a single operation if, for example, a wrong file has been chosen. Killing threads does not work - COPY just keeps running. The FutureTask<> class is used to create the threads, so there is a list of them - one for

问题 address addrId street 1 Berkeley 0 Berkeley name addrId name 0 Fred Jam 1 Bread Mi ... String sql = "select * from address, name"; statement = connection.createStatement(); ResultSet results = statement.executeQuery(sql); ... when this code execute, occur Error Error Message is "java.sql.SQLException: Cannot invoke "[Ljava.lang.String;.clone()" because "columnNames" is null" I want to play "select * from join table" What do i do? Help me please. 来源： https://stackoverflow.com/questions

问题 address addrId street 1 Berkeley 0 Berkeley name addrId name 0 Fred Jam 1 Bread Mi ... String sql = "select * from address, name"; statement = connection.createStatement(); ResultSet results = statement.executeQuery(sql); ... when this code execute, occur Error Error Message is "java.sql.SQLException: Cannot invoke "[Ljava.lang.String;.clone()" because "columnNames" is null" I want to play "select * from join table" What do i do? Help me please. 来源： https://stackoverflow.com/questions

问题 address addrId street 1 Berkeley 0 Berkeley name addrId name 0 Fred Jam 1 Bread Mi ... String sql = "select * from address, name"; statement = connection.createStatement(); ResultSet results = statement.executeQuery(sql); ... when this code execute, occur Error Error Message is "java.sql.SQLException: Cannot invoke "[Ljava.lang.String;.clone()" because "columnNames" is null" I want to play "select * from join table" What do i do? Help me please. 来源： https://stackoverflow.com/questions

问题 address addrId street 1 Berkeley 0 Berkeley name addrId name 0 Fred Jam 1 Bread Mi ... String sql = "select * from address, name"; statement = connection.createStatement(); ResultSet results = statement.executeQuery(sql); ... when this code execute, occur Error Error Message is "java.sql.SQLException: Cannot invoke "[Ljava.lang.String;.clone()" because "columnNames" is null" I want to play "select * from join table" What do i do? Help me please. 来源： https://stackoverflow.com/questions

问题 In one of the questions regarding DBF creation, I found the code below. Did I understand correctly that a DBF file is created here with the names of the columns and the values that will be returned as a result of executing the SQL query? Does println do DBF output? And if everything is so, then how to save the resulting DBF file (name.dbf)? I'm confused and can't figure it out with DBF. I need to create a DBF file and fill it with values by accessing a function in a SQL package. The second

问题 In one of the questions regarding DBF creation, I found the code below. Did I understand correctly that a DBF file is created here with the names of the columns and the values that will be returned as a result of executing the SQL query? Does println do DBF output? And if everything is so, then how to save the resulting DBF file (name.dbf)? I'm confused and can't figure it out with DBF. I need to create a DBF file and fill it with values by accessing a function in a SQL package. The second

问题 Does JDBC result set fetch all data in one network call for a SQL query? Consider the query select * from table where timestamp > 1597937895 . Now there are more than 1 million rows for this query. Does result set fetch all the rows in one network call? Or does it fetch batch of rows as and when the result set is read? Because I need to look at memory usage as well. Hence clarifying. I am known by the fact that ResultSet fetches all data in one network call. Is this is the only behaviour or