/* ** Generate code to drop and reload the internal representation of table ** pTab from the database, including triggers and temporary triggers. ** Argument zName is the name of the table in the database schema at ** the time the generated code is executed. This can be different from ** pTab->zName if this function is being called to code part of an ** "ALTER TABLE RENAME TO" statement. 生成代码删除和重新加载从数据库表pTab的内部表达示, 包括触发器和临时触发器。 参数zName在数据库模式中的表的名称生成的代码执行。 这可以不同于pTab - > zName如果这个函数被调用的代码的一部分“ALTER TABLE RENAME TO”声明。 */ static void reloadTableSchema(Parse *pParse, Table *pTab, const char *zName){ Vdbe *v; char *zWhere; int iDb; /* Index of database containing pTab 包含pTab数据库索引*/ #ifndef SQLITE_OMIT_TRIGGER Trigger *pTrig; #endif v = sqlite3GetVdbe(pParse); if( NEVER(v==0) ) return; assert( sqlite3BtreeHoldsAllMutexes(pParse->db) ); iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema); assert( iDb>=0 ); #ifndef SQLITE_OMIT_TRIGGER /* Drop any table triggers from the internal schema. 降低任何表触发器内部模式。*/ for(pTrig=sqlite3TriggerList(pParse, pTab); pTrig; pTrig=pTrig->pNext){ int iTrigDb = sqlite3SchemaToIndex(pParse->db, pTrig->pSchema); assert( iTrigDb==iDb || iTrigDb==1 ); sqlite3VdbeAddOp4(v, OP_DropTrigger, iTrigDb, 0, 0, pTrig->zName, 0); } #endif /* Drop the table and index from the internal schema. 从内部模式中降低表和索引*/ sqlite3VdbeAddOp4(v, OP_DropTable, iDb, 0, 0, pTab->zName, 0); /* Reload the table, index and permanent trigger schemas. 重载表、索引和不变的触发器模式*/ zWhere = sqlite3MPrintf(pParse->db, "tbl_name=%Q", zName); if( !zWhere ) return; sqlite3VdbeAddParseSchemaOp(v, iDb, zWhere); #ifndef SQLITE_OMIT_TRIGGER /* Now, if the table is not stored in the temp database, reload any temp ** triggers. Don't use IN(...) in case SQLITE_OMIT_SUBQUERY is defined. 现在,如果表没有在临时数据库中存储,那么重载任何临时触发器。 不要用IN(...)在 SQLITE_OMIT_SUBQUERY被默认的情况下。 */ if( (zWhere=whereTempTriggers(pParse, pTab))!=0 ){ sqlite3VdbeAddParseSchemaOp(v, 1, zWhere); } #endif }
/* ** The parser calls this routine after the CREATE VIRTUAL TABLE statement ** has been completely parsed. */ void sqlite3VtabFinishParse(Parse *pParse, Token *pEnd){ Table *pTab = pParse->pNewTable; /* The table being constructed */ sqlite3 *db = pParse->db; /* The database connection */ if( pTab==0 ) return; addArgumentToVtab(pParse); pParse->sArg.z = 0; if( pTab->nModuleArg<1 ) return; /* If the CREATE VIRTUAL TABLE statement is being entered for the ** first time (in other words if the virtual table is actually being ** created now instead of just being read out of sqlite_master) then ** do additional initialization work and store the statement text ** in the sqlite_master table. */ if( !db->init.busy ){ char *zStmt; char *zWhere; int iDb; int iReg; Vdbe *v; /* Compute the complete text of the CREATE VIRTUAL TABLE statement */ if( pEnd ){ pParse->sNameToken.n = (int)(pEnd->z - pParse->sNameToken.z) + pEnd->n; } zStmt = sqlite3MPrintf(db, "CREATE VIRTUAL TABLE %T", &pParse->sNameToken); /* A slot for the record has already been allocated in the ** SQLITE_MASTER table. We just need to update that slot with all ** the information we've collected. ** ** The VM register number pParse->regRowid holds the rowid of an ** entry in the sqlite_master table tht was created for this vtab ** by sqlite3StartTable(). */ iDb = sqlite3SchemaToIndex(db, pTab->pSchema); sqlite3NestedParse(pParse, "UPDATE %Q.%s " "SET type='table', name=%Q, tbl_name=%Q, rootpage=0, sql=%Q " "WHERE rowid=#%d", db->aDb[iDb].zDbSName, MASTER_NAME, pTab->zName, pTab->zName, zStmt, pParse->regRowid ); sqlite3DbFree(db, zStmt); v = sqlite3GetVdbe(pParse); sqlite3ChangeCookie(pParse, iDb); sqlite3VdbeAddOp0(v, OP_Expire); zWhere = sqlite3MPrintf(db, "name='%q' AND type='table'", pTab->zName); sqlite3VdbeAddParseSchemaOp(v, iDb, zWhere); iReg = ++pParse->nMem; sqlite3VdbeLoadString(v, iReg, pTab->zName); sqlite3VdbeAddOp2(v, OP_VCreate, iDb, iReg); } /* If we are rereading the sqlite_master table create the in-memory ** record of the table. The xConnect() method is not called until ** the first time the virtual table is used in an SQL statement. This ** allows a schema that contains virtual tables to be loaded before ** the required virtual table implementations are registered. */ else { Table *pOld; Schema *pSchema = pTab->pSchema; const char *zName = pTab->zName; assert( sqlite3SchemaMutexHeld(db, 0, pSchema) ); pOld = sqlite3HashInsert(&pSchema->tblHash, zName, pTab); if( pOld ){ sqlite3OomFault(db); assert( pTab==pOld ); /* Malloc must have failed inside HashInsert() */ return; } pParse->pNewTable = 0; } }
/* ** This routine is called after all of the trigger actions have been parsed ** in order to complete the process of building the trigger. */ SQLITE_PRIVATE void sqlite3FinishTrigger( Parse *pParse, /* Parser context */ TriggerStep *pStepList, /* The triggered program */ Token *pAll /* Token that describes the complete CREATE TRIGGER */ ){ Trigger *pTrig = pParse->pNewTrigger; /* Trigger being finished */ char *zName; /* Name of trigger */ sqlite3 *db = pParse->db; /* The database */ DbFixer sFix; /* Fixer object */ int iDb; /* Database containing the trigger */ Token nameToken; /* Trigger name for error reporting */ pParse->pNewTrigger = 0; if( NEVER(pParse->nErr) || !pTrig ) goto triggerfinish_cleanup; zName = pTrig->zName; iDb = sqlite3SchemaToIndex(pParse->db, pTrig->pSchema); pTrig->step_list = pStepList; while( pStepList ){ pStepList->pTrig = pTrig; pStepList = pStepList->pNext; } nameToken.z = pTrig->zName; nameToken.n = sqlite3Strlen30(nameToken.z); sqlite3FixInit(&sFix, pParse, iDb, "trigger", &nameToken); if( sqlite3FixTriggerStep(&sFix, pTrig->step_list) || sqlite3FixExpr(&sFix, pTrig->pWhen) ){ goto triggerfinish_cleanup; } /* if we are not initializing, ** build the sqlite_master entry */ if( !db->init.busy ){ Vdbe *v; char *z; /* Make an entry in the sqlite_master table */ v = sqlite3GetVdbe(pParse); if( v==0 ) goto triggerfinish_cleanup; sqlite3BeginWriteOperation(pParse, 0, iDb); z = sqlite3DbStrNDup(db, (char*)pAll->z, pAll->n); sqlite3NestedParse(pParse, "INSERT INTO %Q.%s VALUES('trigger',%Q,%Q,0,'CREATE TRIGGER %q')", db->aDb[iDb].zName, SCHEMA_TABLE(iDb), zName, pTrig->table, z); sqlite3DbFree(db, z); sqlite3ChangeCookie(pParse, iDb); sqlite3VdbeAddParseSchemaOp(v, iDb, sqlite3MPrintf(db, "type='trigger' AND name='%q'", zName)); } if( db->init.busy ){ Trigger *pLink = pTrig; Hash *pHash = &db->aDb[iDb].pSchema->trigHash; assert( sqlite3SchemaMutexHeld(db, iDb, 0) ); pTrig = sqlite3HashInsert(pHash, zName, sqlite3Strlen30(zName), pTrig); if( pTrig ){ db->mallocFailed = 1; }else if( pLink->pSchema==pLink->pTabSchema ){ Table *pTab; int n = sqlite3Strlen30(pLink->table); pTab = sqlite3HashFind(&pLink->pTabSchema->tblHash, pLink->table, n); assert( pTab!=0 ); pLink->pNext = pTab->pTrigger; pTab->pTrigger = pLink; } } triggerfinish_cleanup: sqlite3DeleteTrigger(db, pTrig); assert( !pParse->pNewTrigger ); sqlite3DeleteTriggerStep(db, pStepList); }