/*
** Generate code to implement the "ALTER TABLE xxx RENAME TO yyy"
** command.
*/
void sqlite3AlterRenameTable(
Parse *pParse, /* Parser context. */
SrcList *pSrc, /* The table to rename. */
Token *pName /* The new table name. */
){
int iDb; /* Database that contains the table */
char *zDb; /* Name of database iDb */
Table *pTab; /* Table being renamed */
char *zName = 0; /* NULL-terminated version of pName */
sqlite3 *db = pParse->db; /* Database connection */
int nTabName; /* Number of UTF-8 characters in zTabName */
const char *zTabName; /* Original name of the table */
Vdbe *v;
#ifndef SQLITE_OMIT_TRIGGER
char *zWhere = 0; /* Where clause to locate temp triggers */
#endif
VTable *pVTab = 0; /* Non-zero if this is a v-tab with an xRename() */
int savedDbFlags; /* Saved value of db->flags */
savedDbFlags = db->flags;
if( NEVER(db->mallocFailed) ) goto exit_rename_table;
assert( pSrc->nSrc==1 );
assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
pTab = sqlite3LocateTableItem(pParse, 0, &pSrc->a[0]);
if( !pTab ) goto exit_rename_table;
iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
zDb = db->aDb[iDb].zName;
db->flags |= SQLITE_PreferBuiltin;
/* Get a NULL terminated version of the new table name. */
zName = sqlite3NameFromToken(db, pName);
if( !zName ) goto exit_rename_table;
/* Check that a table or index named 'zName' does not already exist
** in database iDb. If so, this is an error.
*/
if( sqlite3FindTable(db, zName, zDb) || sqlite3FindIndex(db, zName, zDb) ){
sqlite3ErrorMsg(pParse,
"there is already another table or index with this name: %s", zName);
goto exit_rename_table;
}
/* Make sure it is not a system table being altered, or a reserved name
** that the table is being renamed to.
*/
if( SQLITE_OK!=isSystemTable(pParse, pTab->zName) ){
goto exit_rename_table;
}
if( SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){ goto
exit_rename_table;
}
#ifndef SQLITE_OMIT_VIEW
if( pTab->pSelect ){
sqlite3ErrorMsg(pParse, "view %s may not be altered", pTab->zName);
goto exit_rename_table;
}
#endif
#ifndef SQLITE_OMIT_AUTHORIZATION
/* Invoke the authorization callback. */
if( sqlite3AuthCheck(pParse, SQLITE_ALTER_TABLE, zDb, pTab->zName, 0) ){
goto exit_rename_table;
}
#endif
#ifndef SQLITE_OMIT_VIRTUALTABLE
if( sqlite3ViewGetColumnNames(pParse, pTab) ){
goto exit_rename_table;
}
if( IsVirtual(pTab) ){
pVTab = sqlite3GetVTable(db, pTab);
if( pVTab->pVtab->pModule->xRename==0 ){
pVTab = 0;
}
}
#endif
/* Begin a transaction for database iDb.
** Then modify the schema cookie (since the ALTER TABLE modifies the
** schema). Open a statement transaction if the table is a virtual
** table.
*/
v = sqlite3GetVdbe(pParse);
if( v==0 ){
goto exit_rename_table;
}
sqlite3BeginWriteOperation(pParse, pVTab!=0, iDb);
sqlite3ChangeCookie(pParse, iDb);
/* If this is a virtual table, invoke the xRename() function if
** one is defined. The xRename() callback will modify the names
** of any resources used by the v-table implementation (including other
** SQLite tables) that are identified by the name of the virtual table.
*/
#ifndef SQLITE_OMIT_VIRTUALTABLE
if( pVTab ){
int i = ++pParse->nMem;
sqlite3VdbeLoadString(v, i, zName);
sqlite3VdbeAddOp4(v, OP_VRename, i, 0, 0,(const char*)pVTab, P4_VTAB);
sqlite3MayAbort(pParse);
}
#endif
/* figure out how many UTF-8 characters are in zName */
zTabName = pTab->zName;
nTabName = sqlite3Utf8CharLen(zTabName, -1);
#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
if( db->flags&SQLITE_ForeignKeys ){
/* If foreign-key support is enabled, rewrite the CREATE TABLE
** statements corresponding to all child tables of foreign key constraints
** for which the renamed table is the parent table. */
if( (zWhere=whereForeignKeys(pParse, pTab))!=0 ){
sqlite3NestedParse(pParse,
"UPDATE \"%w\".%s SET "
"sql = sqlite_rename_parent(sql, %Q, %Q) "
"WHERE %s;", zDb, SCHEMA_TABLE(iDb), zTabName, zName, zWhere);
sqlite3DbFree(db, zWhere);
}
}
#endif
/* Modify the sqlite_master table to use the new table name. */
sqlite3NestedParse(pParse,
"UPDATE %Q.%s SET "
#ifdef SQLITE_OMIT_TRIGGER
"sql = sqlite_rename_table(sql, %Q), "
#else
"sql = CASE "
"WHEN type = 'trigger' THEN sqlite_rename_trigger(sql, %Q)"
"ELSE sqlite_rename_table(sql, %Q) END, "
#endif
"tbl_name = %Q, "
"name = CASE "
"WHEN type='table' THEN %Q "
"WHEN name LIKE 'sqlite_autoindex%%' AND type='index' THEN "
"'sqlite_autoindex_' || %Q || substr(name,%d+18) "
"ELSE name END "
"WHERE tbl_name=%Q COLLATE nocase AND "
"(type='table' OR type='index' OR type='trigger');",
zDb, SCHEMA_TABLE(iDb), zName, zName, zName,
#ifndef SQLITE_OMIT_TRIGGER
zName,
#endif
zName, nTabName, zTabName
);
#ifndef SQLITE_OMIT_AUTOINCREMENT
/* If the sqlite_sequence table exists in this database, then update
** it with the new table name.
*/
if( sqlite3FindTable(db, "sqlite_sequence", zDb) ){
sqlite3NestedParse(pParse,
"UPDATE \"%w\".sqlite_sequence set name = %Q WHERE name = %Q",
zDb, zName, pTab->zName);
}
#endif
#ifndef SQLITE_OMIT_TRIGGER
/* If there are TEMP triggers on this table, modify the sqlite_temp_master
** table. Don't do this if the table being ALTERed is itself located in
** the temp database.
*/
if( (zWhere=whereTempTriggers(pParse, pTab))!=0 ){
sqlite3NestedParse(pParse,
"UPDATE sqlite_temp_master SET "
"sql = sqlite_rename_trigger(sql, %Q), "
"tbl_name = %Q "
"WHERE %s;", zName, zName, zWhere);
sqlite3DbFree(db, zWhere);
}
#endif
#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
if( db->flags&SQLITE_ForeignKeys ){
FKey *p;
for(p=sqlite3FkReferences(pTab); p; p=p->pNextTo){
Table *pFrom = p->pFrom;
if( pFrom!=pTab ){
reloadTableSchema(pParse, p->pFrom, pFrom->zName);
}
}
}
#endif
/* Drop and reload the internal table schema. */
reloadTableSchema(pParse, pTab, zName);
exit_rename_table:
sqlite3SrcListDelete(db, pSrc);
sqlite3DbFree(db, zName);
db->flags = savedDbFlags;
}
/*
** Generate code to implement the "ALTER TABLE xxx RENAME TO yyy"
** command. 生成代码来实现“ALTER TABLE xxx重命名yyy”命令。
*/
void sqlite3AlterRenameTable(
Parse *pParse, /* Parser context. 语法分析器上下文*/
SrcList *pSrc, /* The table to rename. 重命名的表*/
Token *pName /* The new table name. 新表名*/
){
int iDb; /* Database that contains the table 包含表的数据库*/
char *zDb; /* Name of database iDb 数据库iDb 的名称*/
Table *pTab; /* Table being renamed 正在重命名的表*/
char *zName = 0; /* NULL-terminated version of pName pName的空值终止版本*/
sqlite3 *db = pParse->db; /* Database connection 数据库的连接*/
int nTabName; /* Number of UTF-8 characters in zTabName 在 zTabName里的UTF-8类型的数目*/
const char *zTabName; /* Original name of the table 最初的数据库名称*/
Vdbe *v;
#ifndef SQLITE_OMIT_TRIGGER
char *zWhere = 0; /* Where clause to locate temp triggers Where 子句位于temp触发器*/
#endif
VTable *pVTab = 0; /* Non-zero if this is a v-tab with an xRename() 如果是 一个v-tab 和一个xRename() ，则为零*/
int savedDbFlags; /* Saved value of db->flags db->flags的保留值*/
savedDbFlags = db->flags;
if( NEVER(db->mallocFailed) ) goto exit_rename_table;
assert( pSrc->nSrc==1 );
assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
pTab = sqlite3LocateTable(pParse, 0, pSrc->a[0].zName, pSrc->a[0].zDatabase);
if( !pTab ) goto exit_rename_table;
iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
zDb = db->aDb[iDb].zName;
db->flags |= SQLITE_PreferBuiltin;
/* Get a NULL terminated version of the new table name. 得到一个空终止版本的新表的名称。*/
zName = sqlite3NameFromToken(db, pName);
if( !zName ) goto exit_rename_table;
/* Check that a table or index named 'zName' does not already exist
** in database iDb. If so, this is an error.检查一个表或索引名叫“zName”不存在数据库iDb。
如果是这样,这是一个错误。
*/
if( sqlite3FindTable(db, zName, zDb) || sqlite3FindIndex(db, zName, zDb) ){
sqlite3ErrorMsg(pParse,
"there is already another table or index with this name: %s", zName);
goto exit_rename_table;
}
/* Make sure it is not a system table being altered, or a reserved name
** that the table is being renamed to.
确保它不是一个正在被修改的系统表或者一个正在被重命名的保留的名称表
*/
if( SQLITE_OK!=isSystemTable(pParse, pTab->zName) ){
goto exit_rename_table;
}
if( SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){ goto
exit_rename_table;
}
#ifndef SQLITE_OMIT_VIEW
if( pTab->pSelect ){
sqlite3ErrorMsg(pParse, "view %s may not be altered", pTab->zName);
goto exit_rename_table;
}
#endif
#ifndef SQLITE_OMIT_AUTHORIZATION
/* Invoke the authorization callback. 调用授权回调。*/
if( sqlite3AuthCheck(pParse, SQLITE_ALTER_TABLE, zDb, pTab->zName, 0) ){
goto exit_rename_table;
}
#endif
#ifndef SQLITE_OMIT_VIRTUALTABLE
if( sqlite3ViewGetColumnNames(pParse, pTab) ){
goto exit_rename_table;
}
if( IsVirtual(pTab) ){
pVTab = sqlite3GetVTable(db, pTab);
if( pVTab->pVtab->pModule->xRename==0 ){
pVTab = 0;
}
}
#endif
/* Begin a transaction and code the VerifyCookie for database iDb.
** Then modify the schema cookie (since the ALTER TABLE modifies the
** schema). Open a statement transaction if the table is a virtual
** table.
对于iDb数据库开始一个事务和代码的VerifyCookie。
然后修改模式cookie(因为ALTER TABLE修改模式)。
如果表是一个虚拟表打开一个声明事务。
*/
v = sqlite3GetVdbe(pParse);
if( v==0 ){
goto exit_rename_table;
}
sqlite3BeginWriteOperation(pParse, pVTab!=0, iDb);
sqlite3ChangeCookie(pParse, iDb);
/* If this is a virtual table, invoke the xRename() function if
** one is defined. The xRename() callback will modify the names
** of any resources used by the v-table implementation (including other
** SQLite tables) that are identified by the name of the virtual table.、
如果这是一个虚拟表,调用xRename()函数如果一个定义。
xRename()回调将修改使用v-table实现的任何资源的名字(包括其他SQLite表)，
这个v-table实现是确定的虚拟表的名称。
*/
#ifndef SQLITE_OMIT_VIRTUALTABLE
if( pVTab ){
int i = ++pParse->nMem;
sqlite3VdbeAddOp4(v, OP_String8, 0, i, 0, zName, 0);
sqlite3VdbeAddOp4(v, OP_VRename, i, 0, 0,(const char*)pVTab, P4_VTAB);
sqlite3MayAbort(pParse);
}
#endif
/* figure out how many UTF-8 characters are in zName 算出在zName里有多少utf - 8字符*/
zTabName = pTab->zName;
nTabName = sqlite3Utf8CharLen(zTabName, -1);
#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
if( db->flags&SQLITE_ForeignKeys ){
/* If foreign-key support is enabled, rewrite the CREATE TABLE
** statements corresponding to all child tables of foreign key constraints
** for which the renamed table is the parent table.
如果启用了外键的支持,重写CREATE TABLE语句对应的所有子表的外键约束重命名表的父表。*/
if( (zWhere=whereForeignKeys(pParse, pTab))!=0 ){
sqlite3NestedParse(pParse,
"UPDATE \"%w\".%s SET "
"sql = sqlite_rename_parent(sql, %Q, %Q) "
"WHERE %s;", zDb, SCHEMA_TABLE(iDb), zTabName, zName, zWhere);
sqlite3DbFree(db, zWhere);
}
}
#endif
/* Modify the sqlite_master table to use the new table name. 修改sqlite_master表来使用新的表名。*/
sqlite3NestedParse(pParse,
"UPDATE %Q.%s SET "
#ifdef SQLITE_OMIT_TRIGGER
"sql = sqlite_rename_table(sql, %Q), "
#else
"sql = CASE "
"WHEN type = 'trigger' THEN sqlite_rename_trigger(sql, %Q)"
"ELSE sqlite_rename_table(sql, %Q) END, "
#endif
"tbl_name = %Q, "
"name = CASE "
"WHEN type='table' THEN %Q "
"WHEN name LIKE 'sqlite_autoindex%%' AND type='index' THEN "
"'sqlite_autoindex_' || %Q || substr(name,%d+18) "
"ELSE name END "
"WHERE tbl_name=%Q COLLATE nocase AND "
"(type='table' OR type='index' OR type='trigger');",
zDb, SCHEMA_TABLE(iDb), zName, zName, zName,
#ifndef SQLITE_OMIT_TRIGGER
zName,
#endif
zName, nTabName, zTabName
);
#ifndef SQLITE_OMIT_AUTOINCREMENT
/* If the sqlite_sequence table exists in this database, then update
** it with the new table name.
如果sqlite_sequence表存在于这个数据库中,那么用新表的名称更新它
*/
if( sqlite3FindTable(db, "sqlite_sequence", zDb) ){
sqlite3NestedParse(pParse,
"UPDATE \"%w\".sqlite_sequence set name = %Q WHERE name = %Q",
zDb, zName, pTab->zName);
}
#endif
#ifndef SQLITE_OMIT_TRIGGER
/* If there are TEMP triggers on this table, modify the sqlite_temp_master
** table. Don't do this if the table being ALTERed is itself located in
** the temp database.
如果在这个表上有临时触发器，修改sqlite_temp_master表，
如果表被修改本身就是位于临时数据库，不要做这些。
*/
if( (zWhere=whereTempTriggers(pParse, pTab))!=0 ){
sqlite3NestedParse(pParse,
"UPDATE sqlite_temp_master SET "
"sql = sqlite_rename_trigger(sql, %Q), "
"tbl_name = %Q "
"WHERE %s;", zName, zName, zWhere);
sqlite3DbFree(db, zWhere);
}
#endif
#if !defined(SQLITE_OMIT_FOREIGN_KEY) && !defined(SQLITE_OMIT_TRIGGER)
if( db->flags&SQLITE_ForeignKeys ){
FKey *p;
for(p=sqlite3FkReferences(pTab); p; p=p->pNextTo){
Table *pFrom = p->pFrom;
if( pFrom!=pTab ){
reloadTableSchema(pParse, p->pFrom, pFrom->zName);
}
}
}
#endif
/* Drop and reload the internal table schema. 删除和重新加载内部表模式。*/
reloadTableSchema(pParse, pTab, zName);
exit_rename_table:
sqlite3SrcListDelete(db, pSrc);
sqlite3DbFree(db, zName);
db->flags = savedDbFlags;
}
