Examples with MergeUsing org.h2.command.dml.MergeUsing used on opensource projects

Example 1 with MergeUsing

use of org.h2.command.dml.MergeUsing in project h2database by h2database.

the class Parser method parseMergeUsing.

private MergeUsing parseMergeUsing(Merge oldCommand, int start) {
    MergeUsing command = new MergeUsing(oldCommand);
    currentPrepared = command;
    if (readIf("(")) {
        /* a select query is supplied */
        if (isSelect()) {
            command.setQuery(parseSelect());
            read(")");
        }
        command.setQueryAlias(readFromAlias(null, Collections.singletonList("ON")));
        String[] querySQLOutput = { null };
        List<Column> columnTemplateList = TableView.createQueryColumnTemplateList(null, command.getQuery(), querySQLOutput);
        TableView temporarySourceTableView = createCTEView(command.getQueryAlias(), querySQLOutput[0], columnTemplateList, false, /* no recursion */
        false, /* do not add to session */
        false, /* isPersistent */
        session);
        TableFilter sourceTableFilter = new TableFilter(session, temporarySourceTableView, command.getQueryAlias(), rightsChecked, (Select) command.getQuery(), 0, null);
        command.setSourceTableFilter(sourceTableFilter);
    } else {
        /* Its a table name, simulate a query by building a select query for the table */
        List<String> excludeIdentifiers = Collections.singletonList("ON");
        TableFilter sourceTableFilter = readSimpleTableFilter(0, excludeIdentifiers);
        command.setSourceTableFilter(sourceTableFilter);
        StringBuilder buff = new StringBuilder("SELECT * FROM ");
        appendTableWithSchemaAndAlias(buff, sourceTableFilter.getTable(), sourceTableFilter.getTableAlias());
        Prepared preparedQuery = prepare(session, buff.toString(), null);
        command.setQuery((Select) preparedQuery);
    }
    read("ON");
    read("(");
    Expression condition = readExpression();
    command.setOnCondition(condition);
    read(")");
    if (readIfAll("WHEN", "MATCHED", "THEN")) {
        int startMatched = lastParseIndex;
        if (readIf("UPDATE")) {
            Update updateCommand = new Update(session);
            // currentPrepared = updateCommand;
            TableFilter filter = command.getTargetTableFilter();
            updateCommand.setTableFilter(filter);
            parseUpdateSetClause(updateCommand, filter, startMatched);
            command.setUpdateCommand(updateCommand);
        }
        startMatched = lastParseIndex;
        if (readIf("DELETE")) {
            Delete deleteCommand = new Delete(session);
            TableFilter filter = command.getTargetTableFilter();
            deleteCommand.setTableFilter(filter);
            parseDeleteGivenTable(deleteCommand, null, startMatched);
            command.setDeleteCommand(deleteCommand);
        }
    }
    if (readIfAll("WHEN", "NOT", "MATCHED", "THEN")) {
        if (readIf("INSERT")) {
            Insert insertCommand = new Insert(session);
            insertCommand.setTable(command.getTargetTable());
            parseInsertGivenTable(insertCommand, command.getTargetTable());
            command.setInsertCommand(insertCommand);
        }
    }
    setSQL(command, "MERGE", start);
    // build and prepare the targetMatchQuery ready to test each rows
    // existence in the target table (using source row to match)
    StringBuilder targetMatchQuerySQL = new StringBuilder("SELECT _ROWID_ FROM ");
    appendTableWithSchemaAndAlias(targetMatchQuerySQL, command.getTargetTable(), command.getTargetTableFilter().getTableAlias());
    targetMatchQuerySQL.append(" WHERE ").append(command.getOnCondition().getSQL());
    command.setTargetMatchQuery((Select) parse(targetMatchQuerySQL.toString()));
    return command;
}