org.nbone.persistence.jdbc.dialect.SQLServerDialect Maven / Gradle / Ivy

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package org.nbone.persistence.jdbc.dialect;
/**
 * @author thinking
 */
public class SQLServerDialect extends Dialect{

	public boolean supportsLimitOffset(){
		return false;
	}
	
	public boolean supportsLimit() {
		return true;
	}
	
	static int getAfterSelectInsertPoint(String sql) {
		int selectIndex = sql.toLowerCase().indexOf( "select" );
		final int selectDistinctIndex = sql.toLowerCase().indexOf( "select distinct" );
		return selectIndex + ( selectDistinctIndex == selectIndex ? 15 : 6 );
	}

	public String getLimitString(String sql, int offset, int limit) {
		return getLimitString(sql,offset,null,limit,null);
	}

	public String getLimitString(String querySelect, int offset,String offsetPlaceholder, int limit, String limitPlaceholder) {
		if ( offset > 0 ) {
			throw new UnsupportedOperationException( "sql server has no offset" );
		}
//		if(limitPlaceholder != null) {
//			throw new UnsupportedOperationException(" sql server not support variable limit");
//		}
		
		return new StringBuffer( querySelect.length() + 8 )
				.append( querySelect )
				.insert( getAfterSelectInsertPoint( querySelect ), " top " + limit )
				.toString();
	}
	
	// TODO add Dialect.supportsVariableLimit() for sqlserver 
//	public boolean supportsVariableLimit() {
//		return false;
//	}

}