org.tentackle.sql.backends.AbstractSql92Backend Maven / Gradle / Ivy
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/*
* Tentackle - https://tentackle.org.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package org.tentackle.sql.backends;
import org.tentackle.sql.BackendException;
import org.tentackle.sql.BackendPreparedStatement;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Locale;
import java.util.Set;
/**
* Common to all SQL92 backends.
*
* @author harald
*/
public abstract class AbstractSql92Backend extends AbstractBackend {
/** FOR UPDATE string. */
public static final String SQL_FOR_UPDATE = " FOR UPDATE";
/** COALESCE keyword. */
public static final String SQL_COALESCE = "COALESCE";
/** array of reserved words. */
public static final String[] RESERVED_WORDS_SQL92 = new String[] {
"ABSOLUTE", "ACTION", "ADD", "ALL", "ALLOCATE", "ALTER", "AND", "ANY", "ARE", "AS", "ASC",
"ASSERTION", "AT", "AUTHORIZATION", "AVG", "BEGIN", "BETWEEN", "BIT", "BIT_LENGTH", "BOTH", "BY",
"CALL", "CASCADE", "CASCADED", "CASE", "CAST", "CATALOG", "CHAR", "CHARACTER", "CHARACTER_LENGTH",
"CHAR_LENGTH", "CHECK", "CLOSE", "COALESCE", "COLLATE", "COLLATION", "COLUMN", "COMMENT", "COMMIT",
"CONDITION", "CONNECT", "CONNECTION", "CONSTRAINT", "CONSTRAINTS", "CONTAINS", "CONTINUE", "CONVERT",
"CORRESPONDING", "COUNT", "CREATE", "CROSS", "CURRENT", "CURRENT_DATE", "CURRENT_PATH", "CURRENT_TIME",
"CURRENT_TIMESTAMP", "CURRENT_USER", "CURSOR", "DATE", "DAY", "DEALLOCATE", "DEC", "DECIMAL", "DECLARE",
"DEFAULT", "DEFERRABLE", "DEFERRED", "DELETE", "DESC", "DESCRIBE", "DESCRIPTOR", "DETERMINISTIC",
"DIAGNOSTICS", "DISCONNECT", "DISTINCT", "DO", "DOMAIN", "DOUBLE", "DROP", "ELSE", "ELSEIF", "END",
"ESCAPE", "EXCEPT", "EXCEPTION", "EXEC", "EXECUTE", "EXISTS", "EXIT", "EXTERNAL", "EXTRACT", "FALSE",
"FETCH", "FIRST", "FLOAT", "FOR", "FOREIGN", "FOUND", "FROM", "FULL", "FUNCTION", "GET", "GLOBAL", "GO",
"GOTO", "GRANT", "GROUP", "HANDLER", "HAVING", "HOUR", "IDENTITY", "IF", "IMMEDIATE", "IN", "INDICATOR",
"INITIALLY", "INNER", "INOUT", "INPUT", "INSENSITIVE", "INSERT", "INT", "INTEGER", "INTERSECT",
"INTERVAL", "INTO", "IS", "ISOLATION", "JOIN", "KEY", "LANGUAGE", "LAST", "LEADING", "LEAVE",
"LEFT", "LEVEL", "LIKE", "LOCAL", "LOOP", "LOWER", "MATCH", "MAX", "MIN", "MINUTE", "MODULE",
"MONTH", "NAMES", "NATIONAL", "NATURAL", "NCHAR", "NEXT", "NO", "NOT", "NULL", "NULLIF", "NUMERIC",
"OCTET_LENGTH", "OF", "ON", "ONLY", "OPEN", "OPTION", "OR", "ORDER", "OUT", "OUTER", "OUTPUT",
"OVERLAPS", "PAD", "PARAMETER", "PARTIAL", "PATH", "POSITION", "PRECISION", "PREPARE", "PRESERVE",
"PRIMARY", "PRIOR", "PRIVILEGES", "PROCEDURE", "PUBLIC", "READ", "REAL", "REFERENCES", "RELATIVE",
"REPEAT", "RESIGNAL", "RESTRICT", "RETURN", "RETURNS", "REVOKE", "RIGHT", "ROLLBACK", "ROUTINE",
"ROWS", "SCHEMA", "SCROLL", "SECOND", "SECTION", "SELECT", "SESSION", "SESSION_USER", "SET", "SIGNAL",
"SIZE", "SMALLINT", "SOME", "SPACE", "SPECIFIC", "SQL", "SQLCODE", "SQLERROR", "SQLEXCEPTION",
"SQLSTATE", "SQLWARNING", "SUBSTRING", "SUM", "SYSTEM_USER", "TABLE", "TEMPORARY", "THEN", "TIME",
"TIMESTAMP", "TIMEZONE_HOUR", "TIMEZONE_MINUTE", "TO", "TRAILING", "TRANSACTION", "TRANSLATE",
"TRANSLATION", "TRIM", "TRUE", "UNDO", "UNION", "UNIQUE", "UNKNOWN", "UNTIL", "UPDATE", "UPPER",
"USAGE", "USER", "USING", "VALUE", "VALUES", "VARCHAR", "VARYING", "VIEW", "WHEN",
"WHENEVER", "WHERE", "WHILE", "WITH", "WORK", "WRITE", "YEAR", "ZONE"
};
private Set reservedWords; // set of reserved words (built only once)
/**
* Parent constructor.
*/
public AbstractSql92Backend() {
// see -Xlint:missing-explicit-ctor since Java 16
}
@Override
public synchronized Set getReservedWords() {
if (reservedWords == null) {
reservedWords = new HashSet<>(Arrays.asList(RESERVED_WORDS_SQL92));
}
return reservedWords;
}
@Override
public void buildSelectSql(StringBuilder sqlBuilder, boolean writeLock, int limit, int offset) {
if (limit > 0) {
throw new BackendException("backend " + this + " does not support selects with LIMIT clause");
}
if (offset > 0) {
throw new BackendException("backend " + this + " does not support selects with OFFSET clause");
}
if (isLeadingSelectMissing(sqlBuilder)) {
sqlBuilder.insert(0, SQL_SELECT);
}
if (writeLock) {
sqlBuilder.append(SQL_FOR_UPDATE);
}
}
/**
* Determines whether {@link #buildSelectSql(StringBuilder, boolean, int, int)} must prepend a "SELECT ".
*
* @param sqlBuilder the sql builder
* @return true if leading select keyword is missing
*/
protected boolean isLeadingSelectMissing(StringBuilder sqlBuilder) {
// does not start with SELECT or WITH
String sql = sqlBuilder.toString().toUpperCase(Locale.ROOT);
return !sql.startsWith(SQL_SELECT) && !sql.startsWith("WITH ");
}
@Override
public int setLeadingSelectParameters(BackendPreparedStatement stmt, int limit, int offset) {
if (limit > 0) {
throw new BackendException("backend " + this + " does not support selects with LIMIT clause");
}
if (offset > 0) {
throw new BackendException("backend " + this + " does not support selects with OFFSET clause");
}
return 1;
}
@Override
public int setTrailingSelectParameters(BackendPreparedStatement stmt, int index, int limit, int offset) {
if (limit > 0) {
throw new BackendException("backend " + this + " does not support selects with LIMIT clause");
}
if (offset > 0) {
throw new BackendException("backend " + this + " does not support selects with OFFSET clause");
}
return index;
}
@Override
public String getCoalesceKeyword() {
return SQL_COALESCE;
}
@Override
public String sqlCreateForeignKey(String referencingTableName, String referencingColumnName, String referencedTableName,
String referencedColumnName, String foreignKeyName, boolean composite) {
StringBuilder buf = new StringBuilder(SQL_ALTER_TABLE);
buf.append(referencingTableName);
buf.append(" ADD CONSTRAINT ");
buf.append(foreignKeyName);
buf.append(" FOREIGN KEY (");
buf.append(referencingColumnName);
buf.append(") REFERENCES ");
buf.append(referencedTableName);
buf.append(" (");
buf.append(referencedColumnName);
buf.append(")");
if (composite) {
buf.append(" ON DELETE CASCADE");
}
buf.append(getStatementSeparator()).append('\n');
return buf.toString();
}
@Override
public String sqlDropForeignKey(String referencingTableName, String foreignKeyName) {
StringBuilder buf = new StringBuilder();
buf.append(SQL_ALTER_TABLE).append(referencingTableName).append(" DROP CONSTRAINT ");
if (isDropIfExistsEnabled()) {
buf.append(SQL_IF_EXISTS);
}
buf.append(foreignKeyName).append(getStatementSeparator()).append('\n');
return buf.toString();
}
@Override
public boolean isSequenceSupported() {
return false;
}
@Override
public String sqlCreateSequence(String name, Long start, Long increment) {
throw new BackendException(this + " does not support sequences");
}
@Override
public String sqlCreateSequenceComment(String name, String comment) {
return "";
}
@Override
public String sqlNextFromSequence(String name) {
throw new BackendException(this + " does not support sequences");
}
}