Jackcess等价于简单的SQL SELECT语句

Question

Can someone please explain how I might use Jackcess to implement the equivalent of the following SQL queries?

SELECT name FROM table WHERE id = '1'

SELECT name FROM table INNER JOIN table ON table.id = table2.id

Answer 1

Re: your first query (SELECT ... FROM tableName WHERE ...)

In its simplest form you could use the "Searching for a row with a specific column value" example under "Sample code" on the main Jackcess page here , ie,

Table table = DatabaseBuilder.open(new File("my.mdb")).getTable("MyTable");
Row row = CursorBuilder.findRow(table, Collections.singletonMap("a", "foo"));
if(row != null) {
    System.out.println("Found row where 'a' == 'foo': " + row);
} else {
    System.out.println("Could not find row where 'a' == 'foo'");
}

To loop through multiple matching rows you could do something like this

Table table = DatabaseBuilder.open(new File("my.mdb")).getTable("MyTable");
Cursor cursor = CursorBuilder.createCursor(table);
while (cursor.findNextRow(Collections.singletonMap("a", "foo"))) {
    Row row = cursor.getCurrentRow();
    System.out.println(String.format(
            "a='%s', SomeFieldName='%s'.", 
            row.get("a"), 
            row.get("SomeFieldName")));
}

or, as @jtahlborn suggests in a comment below,

Table table = DatabaseBuilder.open(new File("my.mdb")).getTable("MyTable");
Cursor cursor = CursorBuilder.createCursor(table);
for (Row row : cursor.newIterable().addMatchPattern("a", "foo")) {
    System.out.println(String.format(
            "a='%s', SomeFieldName='%s'.", 
            row.get("a"), 
            row.get("SomeFieldName")));
}

Re: your second query (SELECT ... FROM table1 INNER JOIN table2 ON ...)

You could use one for or while loop (similar to above) to iterate through the relevant rows in one table, and use an inner for or while loop to iterate through the related rows in the other (related) table. If the two tables have an existing "Relationship" in Access (aka "foreign key constraint") Jackcess has a Joiner class that may be of assistance, discussed here .

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If you require further assistance you will need to try writing some code for yourself and then ask a new question showing the code you are attempting to use and the specific issue you have with it.