@Override
public Expression optimize(Session session) {
if (columnResolver == null) {
Schema schema =
session
.getDatabase()
.findSchema(tableAlias == null ? session.getCurrentSchemaName() : tableAlias);
if (schema != null) {
Constant constant = schema.findConstant(columnName);
if (constant != null) {
return (Expression) constant.getValue();
}
}
// 处理在where和having中出现别名的情况，如:
// SELECT id AS A FROM mytable where A>=0
// SELECT id/3 AS A, COUNT(*) FROM mytable GROUP BY A HAVING A>=0
if (select != null) {
for (Expression e : select.getExpressions()) {
if (database.equalsIdentifiers(columnName, e.getAlias()))
return e.getNonAliasExpression().optimize(session);
}
}
String name = columnName;
if (tableAlias != null) {
name = tableAlias + "." + name;
if (schemaName != null) {
name = schemaName + "." + name;
}
}
throw DbException.get(ErrorCode.COLUMN_NOT_FOUND_1, name);
}
return (Expression) columnResolver.optimize(this, column);
}
@Override
public void mapColumns(ColumnResolver resolver, int level) {
if (select == null) select = (Select) resolver.getSelect();
if (resolver instanceof TableFilter
&& resolver.getTableFilter().getTable().supportsColumnFamily()) {
Table t = resolver.getTableFilter().getTable();
// if (!t.isStatic() && t.getRowKeyName().equalsIgnoreCase(columnName)) {
// if (columnFamilyName != null) {
// schemaName = tableAlias;
// tableAlias = columnFamilyName;
// columnFamilyName = null;
// }
// if (tableAlias != null && !database.equalsIdentifiers(tableAlias,
// resolver.getTableAlias())) {
// return;
// }
// if (schemaName != null && !database.equalsIdentifiers(schemaName,
// resolver.getSchemaName())) {
// return;
// }
// mapColumn(resolver, t.getRowKeyColumn(), level);
// return;
// }
if (database.equalsIdentifiers(Column.ROWKEY, columnName)) {
Column col = t.getRowKeyColumn();
if (col != null) {
mapColumn(resolver, col, level);
return;
}
}
if (resolver.getSelect() == null) {
Column c = t.getColumn(columnName);
mapColumn(resolver, c, level);
return;
}
String tableAlias = this.tableAlias;
boolean useAlias = false;
// 当columnFamilyName不存在时，有可能是想使用简化的tableAlias.columnName语法
if (columnFamilyName != null && !t.doesColumnFamilyExist(columnFamilyName)) {
// 不替换原有的tableAlias，因为有可能在另一个table中存在这样的columnFamilyName
tableAlias = columnFamilyName;
if (!t.doesColumnExist(columnName)) return;
useAlias = true;
}
if (tableAlias != null && !database.equalsIdentifiers(tableAlias, resolver.getTableAlias())) {
return;
}
if (schemaName != null && !database.equalsIdentifiers(schemaName, resolver.getSchemaName())) {
return;
}
String fullColumnName;
if (useAlias || columnFamilyName == null) fullColumnName = columnName;
else fullColumnName = t.getFullColumnName(columnFamilyName, columnName);
if (t.doesColumnExist(fullColumnName)) {
Column c = t.getColumn(fullColumnName);
mapColumn(resolver, c, level);
return;
}
} else {
if (columnFamilyName != null) {
schemaName = tableAlias;
tableAlias = columnFamilyName;
columnFamilyName = null;
}
}
if (tableAlias != null && !database.equalsIdentifiers(tableAlias, resolver.getTableAlias())) {
return;
}
if (schemaName != null && !database.equalsIdentifiers(schemaName, resolver.getSchemaName())) {
return;
}
for (Column col : resolver.getColumns()) {
String n = col.getName();
if (database.equalsIdentifiers(columnName, n)) {
mapColumn(resolver, col, level);
return;
}
}
if (database.equalsIdentifiers(Column.ROWID, columnName)) {
Column col = resolver.getRowIdColumn();
if (col != null) {
mapColumn(resolver, col, level);
return;
}
}
Column[] columns = resolver.getSystemColumns();
for (int i = 0; columns != null && i < columns.length; i++) {
Column col = columns[i];
if (database.equalsIdentifiers(columnName, col.getName())) {
mapColumn(resolver, col, level);
return;
}
}
}