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org.jooq.impl.Alias Maven / Gradle / Ivy
/**
* Copyright (c) 2009-2016, Data Geekery GmbH (http://www.datageekery.com)
* All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Other licenses:
* -----------------------------------------------------------------------------
* Commercial licenses for this work are available. These replace the above
* ASL 2.0 and offer limited warranties, support, maintenance, and commercial
* database integrations.
*
* For more information, please visit: http://www.jooq.org/licenses
*
*
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*
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*
*
*/
package org.jooq.impl;
import static java.lang.Boolean.TRUE;
import static java.util.Arrays.asList;
import static org.jooq.Clause.FIELD;
import static org.jooq.Clause.FIELD_ALIAS;
import static org.jooq.Clause.FIELD_REFERENCE;
import static org.jooq.Clause.TABLE;
import static org.jooq.Clause.TABLE_ALIAS;
import static org.jooq.Clause.TABLE_REFERENCE;
// ...
import static org.jooq.SQLDialect.CUBRID;
import static org.jooq.SQLDialect.DERBY;
import static org.jooq.SQLDialect.FIREBIRD;
import static org.jooq.SQLDialect.H2;
// ...
import static org.jooq.SQLDialect.HSQLDB;
// ...
// ...
import static org.jooq.SQLDialect.MARIADB;
import static org.jooq.SQLDialect.MYSQL;
// ...
import static org.jooq.SQLDialect.POSTGRES;
import static org.jooq.SQLDialect.SQLITE;
// ...
// ...
import static org.jooq.impl.DSL.falseCondition;
import static org.jooq.impl.DSL.field;
import static org.jooq.impl.DSL.select;
import static org.jooq.impl.Tools.list;
import static org.jooq.impl.Tools.DataKey.DATA_UNALIAS_ALIASES_IN_ORDER_BY;
import org.jooq.Clause;
import org.jooq.Context;
import org.jooq.Field;
import org.jooq.QueryPart;
import org.jooq.Record;
import org.jooq.SQLDialect;
import org.jooq.Select;
import org.jooq.Table;
/**
* @author Lukas Eder
*/
final class Alias extends AbstractQueryPart {
private static final long serialVersionUID = -2456848365524191614L;
private static final Clause[] CLAUSES_TABLE_REFERENCE = { TABLE, TABLE_REFERENCE };
private static final Clause[] CLAUSES_TABLE_ALIAS = { TABLE, TABLE_ALIAS };
private static final Clause[] CLAUSES_FIELD_REFERENCE = { FIELD, FIELD_REFERENCE };
private static final Clause[] CLAUSES_FIELD_ALIAS = { FIELD, FIELD_ALIAS };
private final Q wrapped;
private final String alias;
private final String[] fieldAliases;
private final boolean wrapInParentheses;
Alias(Q wrapped, String alias) {
this(wrapped, alias, null, false);
}
Alias(Q wrapped, String alias, boolean wrapInParentheses) {
this(wrapped, alias, null, wrapInParentheses);
}
Alias(Q wrapped, String alias, String[] fieldAliases) {
this(wrapped, alias, fieldAliases, false);
}
Alias(Q wrapped, String alias, String[] fieldAliases, boolean wrapInParentheses) {
this.wrapped = wrapped;
this.alias = alias;
this.fieldAliases = fieldAliases;
this.wrapInParentheses = wrapInParentheses;
}
final Q wrapped() {
return wrapped;
}
@Override
public final void accept(Context context) {
if (context.declareAliases() && (context.declareFields() || context.declareTables())) {
context.declareAliases(false);
SQLDialect family = context.family();
boolean emulatedDerivedColumnList = false;
// [#454] [#1801] Some databases don't allow "derived column names" in
// "simple class specifications", or "common table expression references".
// Hence, wrap the table reference in a subselect
if (fieldAliases != null
&& asList(CUBRID, FIREBIRD).contains(family)
&& (wrapped instanceof TableImpl || wrapped instanceof CommonTableExpressionImpl)) {
Select select =
select(list(field("*"))).from(((Table) wrapped).as(alias));
context.sql('(').formatIndentStart().formatNewLine()
.visit(select).formatIndentEnd().formatNewLine()
.sql(')');
}
// [#1801] Some databases do not support "derived column names".
// They can be emulated by concatenating a dummy SELECT with no
// results using UNION ALL
else if (fieldAliases != null && asList(H2, MARIADB, MYSQL, SQLITE).contains(family)) {
emulatedDerivedColumnList = true;
SelectFieldList fields = new SelectFieldList();
for (String fieldAlias : fieldAliases) {
switch (family) {
default: {
fields.add(field("null").as(fieldAlias));
break;
}
}
}
Select select = select(fields).where(falseCondition())
.unionAll(
// [#3156] Do not SELECT * from derived tables to prevent ambiguously defined columns
// in those derived tables
wrapped instanceof Select
? (Select) wrapped
: wrapped instanceof DerivedTable
? ((DerivedTable) wrapped).query()
: select(field("*")).from(((Table) wrapped).as(alias))
);
context.sql('(').formatIndentStart().formatNewLine()
.visit(select).formatIndentEnd().formatNewLine()
.sql(')');
}
// The default behaviour
else {
toSQLWrapped(context);
}
// [#291] some aliases cause trouble, if they are not explicitly marked using "as"
toSQLAs(context);
context.sql(' ');
context.literal(alias);
// [#1801] Add field aliases to the table alias, if applicable
if (fieldAliases != null && !emulatedDerivedColumnList) {
toSQLDerivedColumnList(context);
}
else {
// [#756] If the aliased object is an anonymous table (usually an
// unnested array), then field names must be part of the alias
// declaration. For example:
//
// SELECT t.column_value FROM UNNEST(ARRAY[1, 2]) AS t(column_value)
// TODO: Is this still needed?
switch (family) {
case HSQLDB:
case POSTGRES: {
// The javac compiler doesn't like casting of generics
Object o = wrapped;
if (context.declareTables() && o instanceof ArrayTable) {
ArrayTable table = (ArrayTable) o;
context.sql('(');
Tools.fieldNames(context, table.fields());
context.sql(')');
}
break;
}
}
}
context.declareAliases(true);
}
else {
context.literal(alias);
}
}
static void toSQLAs(Context context) {
if (asList(DERBY, HSQLDB, MARIADB, MYSQL, POSTGRES).contains(context.family())) {
context.sql(' ').keyword("as");
}
}
private void toSQLWrapped(Context context) {
context.sql(wrapInParentheses ? "(" : "")
.visit(wrapped)
.sql(wrapInParentheses ? ")" : "");
}
private void toSQLDerivedColumnList(Context context) {
String separator = "";
context.sql('(');
for (int i = 0; i < fieldAliases.length; i++) {
context.sql(separator);
context.literal(fieldAliases[i]);
separator = ", ";
}
context.sql(')');
}
@Override
public final Clause[] clauses(Context ctx) {
if (ctx.declareFields() || ctx.declareTables()) {
if (wrapped instanceof Table)
return CLAUSES_TABLE_ALIAS;
else
return CLAUSES_FIELD_ALIAS;
}
else {
if (wrapped instanceof Table)
return CLAUSES_TABLE_REFERENCE;
else
return CLAUSES_FIELD_REFERENCE;
}
}
@Override
public final boolean declaresFields() {
return true;
}
@Override
public final boolean declaresTables() {
return true;
}
}
