Feature #4203 - DROP [IF EXISTS] (#7946)

Author: asfernandes

doc/sql.extensions/README.ddl.txt

@@ -629,3 +629,32 @@ Only users with administrator rights can use this option.
 (Dmitry Sibiryakov)
 
 If is used twice, an error is returned.
+
+
+DDL enhancements in Firebird v6.
+--------------------------------
+
+1) DROP [IF EXISTS]
+
+Using subclause IF EXISTS, it's now possible to try to drop objects and do not get errors when they di not exists.
+
+DROP EXCEPTION [IF EXISTS] <exception>
+DROP INDEX [IF EXISTS] <index>
+DROP PROCEDURE [IF EXISTS] <procedure>
+DROP TABLE [IF EXISTS] <table>
+DROP TRIGGER [IF EXISTS] <trigger>
+DROP VIEW [IF EXISTS] <view>
+DROP FILTER [IF EXISTS] <filter>
+DROP DOMAIN [IF EXISTS] <domain>
+DROP [EXTERNAL] FUNCTION [IF EXISTS] <function>
+DROP SHADOW [IF EXISTS] <shadow>
+DROP ROLE [IF EXISTS] <role>
+DROP GENERATOR [IF EXISTS] <generator>
+DROP SEQUENCE [IF EXISTS] <sequence>
+DROP COLLATION [IF EXISTS] <collation>
+DROP USER [IF EXISTS] <user> [USING PLUGIN <plugin>]
+DROP PACKAGE [IF EXISTS] <package>
+DROP PACKAGE BODY [IF EXISTS] <package>
+DROP [GLOBAL] MAPPING [IF EXISTS] <mapping>
+ALTER TABLE <table> DROP [IF EXISTS] <column>
+ALTER TABLE <table> DROP CONSTRAINT [IF EXISTS] <constraint>

src/dsql/DdlNodes.epp

@@ -4335,7 +4335,7 @@ void DropCollationNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratc
 		executeDdlTrigger(tdbb, dsqlScratch, transaction, DTW_AFTER, DDL_TRIGGER_DROP_COLLATION,
 			name, NULL);
 	}
-	else
+	else if (!silent)
 		status_exception::raise(Arg::Gds(isc_dyn_collation_not_found) << Arg::Str(name));
 
 	savePoint.release();	// everything is ok
@@ -5406,7 +5406,7 @@ void DropDomainNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratch,
 		executeDdlTrigger(tdbb, dsqlScratch, transaction, DTW_AFTER, DDL_TRIGGER_DROP_DOMAIN,
 			name, NULL);
 	}
-	else
+	else if (!silent)
 	{
 		// msg 89: "Domain not found"
 		status_exception::raise(Arg::PrivateDyn(89));
@@ -6236,7 +6236,7 @@ void RelationNode::FieldDefinition::store(thread_db* tdbb, jrd_tra* transaction)
 // done by code and system triggers. See the functional description of
 // deleteKeyConstraint function for detail.
 void RelationNode::deleteLocalField(thread_db* tdbb, jrd_tra* transaction,
-	const MetaName& relationName, const MetaName& fieldName)
+	const MetaName& relationName, const MetaName& fieldName, bool silent)
 {
 	AutoCacheRequest request(tdbb, drq_l_dep_flds, DYN_REQUESTS);
 	bool found = false;
@@ -6358,7 +6358,7 @@ void RelationNode::deleteLocalField(thread_db* tdbb, jrd_tra* transaction,
 	}
 	END_FOR
 
-	if (!found)
+	if (!found && !silent)
 	{
 		// msg 176: "column %s does not exist in table/view %s"
 		status_exception::raise(Arg::PrivateDyn(176) << fieldName << relationName);
@@ -7828,7 +7828,7 @@ void AlterRelationNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratc
 							Arg::Gds(isc_dsql_construct_err));
 					}
 
-					deleteLocalField(tdbb, transaction, name, clause->name);
+					deleteLocalField(tdbb, transaction, name, clause->name, clause->silent);
 					break;
 				}
 
@@ -7840,8 +7840,8 @@ void AlterRelationNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratc
 				case Clause::TYPE_DROP_CONSTRAINT:
 				{
 					CreateDropConstraint& dropConstraint = constraints.add();
-					dropConstraint.name =
-						static_cast<const DropConstraintClause*>(i->getObject())->name;
+					dropConstraint.name = static_cast<const DropConstraintClause*>(i->getObject())->name;
+					dropConstraint.silent = static_cast<const DropConstraintClause*>(i->getObject())->silent;
 					break;
 				}
 
@@ -7933,7 +7933,7 @@ void AlterRelationNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratc
 				}
 				END_FOR
 
-				if (!found)
+				if (!found && !constraint->silent)
 				{
 					// msg 130: "CONSTRAINT %s does not exist."
 					status_exception::raise(Arg::PrivateDyn(130) << constraint->name);
@@ -9222,7 +9222,7 @@ void CreateAlterViewNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScra
 		for (dsql_fld* relField = modifyingView->rel_fields; relField; relField = relField->fld_next)
 		{
 			if (!modifiedFields.exist(relField))
-				deleteLocalField(tdbb, transaction, name, relField->fld_name);
+				deleteLocalField(tdbb, transaction, name, relField->fld_name, false);
 		}
 	}
 
@@ -10154,7 +10154,7 @@ void DropIndexNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratch, j
 		executeDdlTrigger(tdbb, dsqlScratch, transaction, DTW_AFTER, DDL_TRIGGER_DROP_INDEX,
 			name, NULL);
 	}
-	else
+	else if (!silent)
 	{
 		// msg 48: "Index not found"
 		status_exception::raise(Arg::PrivateDyn(48));
@@ -10283,7 +10283,7 @@ void DropFilterNode::execute(thread_db* tdbb, DsqlCompilerScratch* /*dsqlScratch
 	}
 	END_FOR
 
-	if (!found)
+	if (!found && !silent)
 	{
 		// msg 37: "Blob Filter %s not found"
 		status_exception::raise(Arg::PrivateDyn(37) << name);
@@ -10990,19 +10990,24 @@ void MappingNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratch, jrd
 		break;
 
 	case MAP_MOD:
-	case MAP_DROP:
 	case MAP_COMMENT:
 		if (!found)
 			(Arg::Gds(isc_map_not_exists) << name).raise();
 		break;
+
+	case MAP_DROP:
+		if (!found && !silentDrop)
+			(Arg::Gds(isc_map_not_exists) << name).raise();
+		break;
 	}
 
-	fb_assert(ddlTriggerAction > 0 || op == MAP_COMMENT);
+	fb_assert(ddlTriggerAction > 0 || op == MAP_COMMENT || (op == MAP_DROP && silentDrop));
 	if (ddlTriggerAction > 0)
 		executeDdlTrigger(tdbb, dsqlScratch, transaction, DTW_AFTER, ddlTriggerAction, name, NULL);
 
 	if (op != MAP_COMMENT)
 		DFW_post_work(transaction, dfw_clear_cache, NULL, Mapping::MAPPING_CACHE);
+
 	savePoint.release();	// everything is ok
 }
 
@@ -11083,7 +11088,7 @@ void DropRoleNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratch, jr
 		executeDdlTrigger(tdbb, dsqlScratch, transaction, DTW_AFTER, DDL_TRIGGER_DROP_ROLE,
 			name, NULL);
 	}
-	else
+	else if (!silent)
 	{
 		// msg 155: "Role %s not found"
 		status_exception::raise(Arg::PrivateDyn(155) << name);

src/dsql/DdlNodes.h

@@ -918,6 +918,7 @@ class DropCollationNode : public DdlNode
 
 public:
 	MetaName name;
+	bool silent = false;
 };
 
 
@@ -1025,6 +1026,7 @@ class DropDomainNode : public DdlNode
 
 public:
 	MetaName name;
+	bool silent = false;
 };
 
 
@@ -1301,6 +1303,7 @@ class RelationNode : public DdlNode
 
 		MetaName name;
 		Firebird::AutoPtr<Constraint> create;
+		bool silent = false;
 	};
 
 	struct Clause
@@ -1484,13 +1487,13 @@ class RelationNode : public DdlNode
 	{
 		explicit DropColumnClause(MemoryPool& p)
 			: Clause(p, TYPE_DROP_COLUMN),
-			  name(p),
-			  cascade(false)
+			  name(p)
 		{
 		}
 
 		MetaName name;
-		bool cascade;
+		bool cascade = false;
+		bool silent = false;
 	};
 
 	struct DropConstraintClause : public Clause
@@ -1502,12 +1505,13 @@ class RelationNode : public DdlNode
 		}
 
 		MetaName name;
+		bool silent = false;
 	};
 
 	RelationNode(MemoryPool& p, RelationSourceNode* aDsqlNode);
 
 	static void deleteLocalField(thread_db* tdbb, jrd_tra* transaction,
-		const MetaName& relationName, const MetaName& fieldName);
+		const MetaName& relationName, const MetaName& fieldName, bool silent);
 
 	static void addToPublication(thread_db* tdbb, jrd_tra* transaction,
 		const MetaName& tableName, const MetaName& pubTame);
@@ -1858,6 +1862,7 @@ class DropIndexNode : public DdlNode
 
 public:
 	MetaName name;
+	bool silent = false;
 };
 
 
@@ -1946,6 +1951,7 @@ class DropFilterNode : public DdlNode
 
 public:
 	MetaName name;
+	bool silent = false;
 };
 
 
@@ -2081,16 +2087,7 @@ class MappingNode : public DdlNode, private ExecInSecurityDb
 		: DdlNode(p),
 		  name(p, nm),
 		  fromUtf8(p),
-		  plugin(NULL),
-		  db(NULL),
-		  fromType(NULL),
-		  from(NULL),
-		  to(NULL),
-		  comment(NULL),
-		  op(o),
-		  mode('#'),
-		  global(false),
-		  role(false)
+		  op(o)
 	{
 	}
 
@@ -2117,16 +2114,17 @@ class MappingNode : public DdlNode, private ExecInSecurityDb
 public:
 	MetaName name;
 	Firebird::string fromUtf8;
-	MetaName* plugin;
-	MetaName* db;
-	MetaName* fromType;
-	IntlString* from;
-	MetaName* to;
-	Firebird::string* comment;
+	MetaName* plugin = nullptr;
+	MetaName* db = nullptr;
+	MetaName* fromType = nullptr;
+	IntlString* from = nullptr;
+	MetaName* to = nullptr;
+	Firebird::string* comment = nullptr;
 	OP op;
-	char mode;	// * - any source, P - plugin, M - mapping, S - any serverwide plugin
-	bool global;
-	bool role;
+	char mode = '#';	// * - any source, P - plugin, M - mapping, S - any serverwide plugin
+	bool global = false;
+	bool role = false;
+	bool silentDrop = false;
 };
 
 
@@ -2152,6 +2150,7 @@ class DropRoleNode : public DdlNode
 
 public:
 	MetaName name;
+	bool silent = false;
 };
 
 

src/dsql/parse-conflicts.txt

@@ -1 +1 @@
-71 shift/reduce conflicts, 22 reduce/reduce conflicts.
+94 shift/reduce conflicts, 22 reduce/reduce conflicts.