public static void sqlite3Update(Parse parse, SrcList tabList, ExprList changes, Expr where_, OE onError)
{
int i, j; // Loop counters
AuthContext sContext = new AuthContext(); // The authorization context
Context ctx = parse.Ctx; // The database structure
if (parse.Errs != 0 || ctx.MallocFailed)
{
goto update_cleanup;
}
Debug.Assert(tabList.Srcs == 1);
// Locate the table which we want to update.
Table table = sqlite3SrcListLookup(parse, tabList); // The table to be updated
if (table == null)
{
goto update_cleanup;
}
int db = sqlite3SchemaToIndex(ctx, table.Schema); // Database containing the table being updated
// Figure out if we have any triggers and if the table being updated is a view.
#if !OMIT_TRIGGER
int tmask = 0; // Mask of TRIGGER_BEFORE|TRIGGER_AFTER
Trigger trigger = sqlite3TriggersExist(parse, table, TK.UPDATE, changes, out tmask); // List of triggers on pTab, if required
#if OMIT_VIEW
const bool isView = false;
#else
bool isView = (table.Select != null); // True when updating a view (INSTEAD OF trigger)
#endif
Debug.Assert(trigger != null || tmask == 0);
#else
const Trigger trigger = null;
const int tmask = 0;
const bool isView = false;
#endif
if (sqlite3ViewGetColumnNames(parse, table) != 0 || sqlite3IsReadOnly(parse, table, tmask))
{
goto update_cleanup;
}
int[] xrefs = new int[table.Cols.length]; // xrefs[i] is the index in pChanges->a[] of the an expression for the i-th column of the table. xrefs[i]==-1 if the i-th column is not changed.
if (xrefs == null)
{
goto update_cleanup;
}
for (i = 0; i < table.Cols.length; i++)
{
xrefs[i] = -1;
}
// Allocate a cursors for the main database table and for all indices. The index cursors might not be used, but if they are used they
// need to occur right after the database cursor. So go ahead and allocate enough space, just in case.
int curId; // VDBE Cursor number of pTab
tabList.Ids[0].Cursor = curId = parse.Tabs++;
Index idx; // For looping over indices
for (idx = table.Index; idx != null; idx = idx.Next)
{
parse.Tabs++;
}
// Initialize the name-context
NameContext sNC = new NameContext(); // The name-context to resolve expressions in
sNC.Parse = parse;
sNC.SrcList = tabList;
// Resolve the column names in all the expressions of the of the UPDATE statement. Also find the column index
// for each column to be updated in the pChanges array. For each column to be updated, make sure we have authorization to change that column.
bool chngRowid = false; // True if the record number is being changed
Expr rowidExpr = null; // Expression defining the new record number
for (i = 0; i < changes.Exprs; i++)
{
if (sqlite3ResolveExprNames(sNC, ref changes.Ids[i].Expr) != 0)
{
goto update_cleanup;
}
for (j = 0; j < table.Cols.length; j++)
{
if (string.Equals(table.Cols[j].Name, changes.Ids[i].Name, StringComparison.OrdinalIgnoreCase))
{
if (j == table.PKey)
{
chngRowid = true;
rowidExpr = changes.Ids[i].Expr;
}
xrefs[j] = i;
break;
}
}
if (j >= table.Cols.length)
{
if (Expr::IsRowid(changes.Ids[i].Name))
{
chngRowid = true;
rowidExpr = changes.Ids[i].Expr;
}
else
{
parse.ErrorMsg("no such column: %s", changes.Ids[i].Name);
parse.CheckSchema = 1;
goto update_cleanup;
}
}
#if !OMIT_AUTHORIZATION
{
ARC rc = Auth.Check(parse, AUTH.UPDATE, table.Name, table.Cols[j].Name, ctx.DBs[db].Name);
if (rc == ARC.DENY)
{
goto update_cleanup;
}
else if (rc == ARC.IGNORE)
{
xrefs[j] = -1;
}
}
#endif
}
bool hasFK = sqlite3FkRequired(parse, table, xrefs, chngRowid ? 1 : 0); // True if foreign key processing is required
// Allocate memory for the array aRegIdx[]. There is one entry in the array for each index associated with table being updated. Fill in
// the value with a register number for indices that are to be used and with zero for unused indices.
int idxLength; // Number of indices that need updating
for (idxLength = 0, idx = table.Index; idx != null; idx = idx.Next, idxLength++)
{
;
}
int[] regIdxs = null; // One register assigned to each index to be updated
if (idxLength > 0)
{
regIdxs = new int[idxLength];
if (regIdxs == null)
{
goto update_cleanup;
}
}
for (j = 0, idx = table.Index; idx != null; idx = idx.Next, j++)
{
int regId;
if (hasFK || chngRowid)
{
regId = ++parse.Mems;
}
else
{
regId = 0;
for (i = 0; i < idx.Columns.length; i++)
{
if (xrefs[idx.Columns[i]] >= 0)
{
regId = ++parse.Mems;
break;
}
}
}
regIdxs[j] = regId;
}
// Begin generating code.
Vdbe v = parse.GetVdbe(); // The virtual database engine
if (v == null)
{
goto update_cleanup;
}
if (parse.Nested == 0)
{
v.CountChanges();
}
parse.BeginWriteOperation(1, db);
#if !OMIT_VIRTUALTABLE
// Virtual tables must be handled separately
if (IsVirtual(table))
{
UpdateVirtualTable(parse, tabList, table, changes, rowidExpr, xrefs, where_, onError);
where_ = null;
tabList = null;
goto update_cleanup;
}
#endif
// Register Allocations
int regRowCount = 0; // A count of rows changed
int regOldRowid; // The old rowid
int regNewRowid; // The new rowid
int regNew;
int regOld = 0;
int regRowSet = 0; // Rowset of rows to be updated
// Allocate required registers.
regOldRowid = regNewRowid = ++parse.Mems;
if (trigger != null || hasFK)
{
regOld = parse.Mems + 1;
parse.Mems += table.Cols.length;
}
if (chngRowid || trigger != null || hasFK)
{
regNewRowid = ++parse.Mems;
}
regNew = parse.Mems + 1;
parse.Mems += table.Cols.length;
// Start the view context.
if (isView)
{
Auth.ContextPush(parse, sContext, table.Name);
}
// If we are trying to update a view, realize that view into a ephemeral table.
#if !OMIT_VIEW && !OMIT_TRIGGER
if (isView)
{
sqlite3MaterializeView(parse, table, where_, curId);
}
#endif
// Resolve the column names in all the expressions in the WHERE clause.
if (sqlite3ResolveExprNames(sNC, ref where_) != 0)
{
goto update_cleanup;
}
// Begin the database scan
v.AddOp2(OP.Null, 0, regOldRowid);
ExprList dummy = null;
WhereInfo winfo = Where.Begin(parse, tabList, where_, ref dummy, WHERE.ONEPASS_DESIRED); // Information about the WHERE clause
if (winfo == null)
{
goto update_cleanup;
}
bool okOnePass = winfo.OkOnePass; // True for one-pass algorithm without the FIFO
// Remember the rowid of every item to be updated.
v.AddOp2(OP.Rowid, curId, regOldRowid);
if (!okOnePass)
{
v.AddOp2(OP.RowSetAdd, regRowSet, regOldRowid);
}
// End the database scan loop.
Where.End(winfo);
// Initialize the count of updated rows
if ((ctx.Flags & Context.FLAG.CountRows) != 0 && parse.TriggerTab == null)
{
regRowCount = ++parse.Mems;
v.AddOp2(OP.Integer, 0, regRowCount);
}
bool openAll = false; // True if all indices need to be opened
if (!isView)
{
// Open every index that needs updating. Note that if any index could potentially invoke a REPLACE conflict resolution
// action, then we need to open all indices because we might need to be deleting some records.
if (!okOnePass)
{
sqlite3OpenTable(parse, curId, db, table, OP.OpenWrite);
}
if (onError == OE.Replace)
{
openAll = true;
}
else
{
openAll = false;
for (idx = table.Index; idx != null; idx = idx.Next)
{
if (idx.OnError == OE.Replace)
{
openAll = true;
break;
}
}
}
for (i = 0, idx = table.Index; idx != null; idx = idx.Next, i++)
{
if (openAll || regIdxs[i] > 0)
{
KeyInfo key = sqlite3IndexKeyinfo(parse, idx);
v.AddOp4(OP.OpenWrite, curId + i + 1, idx.Id, db, key, Vdbe.P4T.KEYINFO_HANDOFF);
Debug.Assert(parse.Tabs > curId + i + 1);
}
}
}
// Top of the update loop
int addr = 0; // VDBE instruction address of the start of the loop
if (okOnePass)
{
int a1 = v.AddOp1(OP.NotNull, regOldRowid);
addr = v.AddOp0(OP.Goto);
v.JumpHere(a1);
}
else
{
addr = v.AddOp3(OP.RowSetRead, regRowSet, 0, regOldRowid);
}
// Make cursor iCur point to the record that is being updated. If this record does not exist for some reason (deleted by a trigger,
// for example, then jump to the next iteration of the RowSet loop.
v.AddOp3(OP.NotExists, curId, addr, regOldRowid);
// If the record number will change, set register regNewRowid to contain the new value. If the record number is not being modified,
// then regNewRowid is the same register as regOldRowid, which is already populated.
Debug.Assert(chngRowid || trigger != null || hasFK || regOldRowid == regNewRowid);
if (chngRowid)
{
Expr.Code(parse, rowidExpr, regNewRowid);
v.AddOp1(OP.MustBeInt, regNewRowid);
}
// If there are triggers on this table, populate an array of registers with the required old.* column data.
if (hasFK || trigger != null)
{
uint oldmask = (hasFK ? sqlite3FkOldmask(parse, table) : 0);
oldmask |= sqlite3TriggerColmask(parse, trigger, changes, 0, TRIGGER_BEFORE | TRIGGER_AFTER, table, onError);
for (i = 0; i < table.Cols.length; i++)
{
if (xrefs[i] < 0 || oldmask == 0xffffffff || (i < 32 && 0 != (oldmask & (1 << i))))
{
Expr.CodeGetColumnOfTable(v, table, curId, i, regOld + i);
}
else
{
v.AddOp2(OP.Null, 0, regOld + i);
}
}
if (!chngRowid)
{
v.AddOp2(OP.Copy, regOldRowid, regNewRowid);
}
}
// Populate the array of registers beginning at regNew with the new row data. This array is used to check constaints, create the new
// table and index records, and as the values for any new.* references made by triggers.
//
// If there are one or more BEFORE triggers, then do not populate the registers associated with columns that are (a) not modified by
// this UPDATE statement and (b) not accessed by new.* references. The values for registers not modified by the UPDATE must be reloaded from
// the database after the BEFORE triggers are fired anyway (as the trigger may have modified them). So not loading those that are not going to
// be used eliminates some redundant opcodes.
int newmask = (int)sqlite3TriggerColmask(parse, trigger, changes, 1, TRIGGER_BEFORE, table, onError); // Mask of NEW.* columns accessed by BEFORE triggers
for (i = 0; i < table.Cols.length; i++)
{
if (i == table.PKey)
{
//v.AddOp2(OP.Null, 0, regNew + i);
}
else
{
j = xrefs[i];
if (j >= 0)
{
Expr.Code(parse, changes.Ids[j].Expr, regNew + i);
}
else if ((tmask & TRIGGER_BEFORE) == 0 || i > 31 || (newmask & (1 << i)) != 0)
{
// This branch loads the value of a column that will not be changed into a register. This is done if there are no BEFORE triggers, or
// if there are one or more BEFORE triggers that use this value via a new.* reference in a trigger program.
C.ASSERTCOVERAGE(i == 31);
C.ASSERTCOVERAGE(i == 32);
v.AddOp3(OP.Column, curId, i, regNew + i);
v.ColumnDefault(table, i, regNew + i);
}
}
}
// Fire any BEFORE UPDATE triggers. This happens before constraints are verified. One could argue that this is wrong.
if ((tmask & TRIGGER_BEFORE) != 0)
{
v.AddOp2(OP.Affinity, regNew, table.Cols.length);
sqlite3TableAffinityStr(v, table);
sqlite3CodeRowTrigger(parse, trigger, TK.UPDATE, changes, TRIGGER_BEFORE, table, regOldRowid, onError, addr);
// The row-trigger may have deleted the row being updated. In this case, jump to the next row. No updates or AFTER triggers are
// required. This behavior - what happens when the row being updated is deleted or renamed by a BEFORE trigger - is left undefined in the documentation.
v.AddOp3(OP.NotExists, curId, addr, regOldRowid);
// If it did not delete it, the row-trigger may still have modified some of the columns of the row being updated. Load the values for
// all columns not modified by the update statement into their registers in case this has happened.
for (i = 0; i < table.Cols.length; i++)
{
if (xrefs[i] < 0 && i != table.PKey)
{
v.AddOp3(OP.Column, curId, i, regNew + i);
v.ColumnDefault(table, i, regNew + i);
}
}
}
if (!isView)
{
// Do constraint checks.
int dummy2;
sqlite3GenerateConstraintChecks(parse, table, curId, regNewRowid, regIdxs, (chngRowid ? regOldRowid : 0), true, onError, addr, out dummy2);
// Do FK constraint checks.
if (hasFK)
{
sqlite3FkCheck(parse, table, regOldRowid, 0);
}
// Delete the index entries associated with the current record.
int j1 = v.AddOp3(OP.NotExists, curId, 0, regOldRowid); // Address of jump instruction
sqlite3GenerateRowIndexDelete(parse, table, curId, regIdxs);
// If changing the record number, delete the old record.
if (hasFK || chngRowid)
{
v.AddOp2(OP.Delete, curId, 0);
}
v.JumpHere(j1);
if (hasFK)
{
sqlite3FkCheck(parse, table, 0, regNewRowid);
}
// Insert the new index entries and the new record.
sqlite3CompleteInsertion(parse, table, curId, regNewRowid, regIdxs, true, false, false);
// Do any ON CASCADE, SET NULL or SET DEFAULT operations required to handle rows (possibly in other tables) that refer via a foreign key
// to the row just updated.
if (hasFK)
{
sqlite3FkActions(parse, table, changes, regOldRowid);
}
}
// Increment the row counter
if ((ctx.Flags & Context.FLAG.CountRows) != 0 && parse.TriggerTab == null)
{
v.AddOp2(OP.AddImm, regRowCount, 1);
}
sqlite3CodeRowTrigger(parse, trigger, TK.UPDATE, changes, TRIGGER_AFTER, table, regOldRowid, onError, addr);
// Repeat the above with the next record to be updated, until all record selected by the WHERE clause have been updated.
v.AddOp2(OP.Goto, 0, addr);
v.JumpHere(addr);
// Close all tables
Debug.Assert(regIdxs != null);
for (i = 0, idx = table.Index; idx != null; idx = idx.Next, i++)
{
if (openAll || regIdxs[i] > 0)
{
v.AddOp2(OP.Close, curId + i + 1, 0);
}
}
v.AddOp2(OP.Close, curId, 0);
// Update the sqlite_sequence table by storing the content of the maximum rowid counter values recorded while inserting into
// autoincrement tables.
if (parse.Nested == 0 && parse.TriggerTab == null)
{
sqlite3AutoincrementEnd(parse);
}
// Return the number of rows that were changed. If this routine is generating code because of a call to sqlite3NestedParse(), do not
// invoke the callback function.
if ((ctx.Flags & Context.FLAG.CountRows) != 0 && parse.TriggerTab == null && parse.Nested == 0)
{
v.AddOp2(OP.ResultRow, regRowCount, 1);
v.SetNumCols(1);
v.SetColName(0, COLNAME_NAME, "rows updated", SQLITE_STATIC);
}
update_cleanup:
#if !OMIT_AUTHORIZATION
Auth.ContextPop(sContext);
#endif
C._tagfree(ctx, ref regIdxs);
C._tagfree(ctx, ref xrefs);
SrcList.Delete(ctx, ref tabList);
ExprList.Delete(ctx, ref changes);
Expr.Delete(ctx, ref where_);
return;
}
public static void DeleteFrom(Parse parse, SrcList tabList, Expr where_)
{
AuthContext sContext = new AuthContext(); // Authorization context
Context ctx = parse.Ctx; // Main database structure
if (parse.Errs != 0 || ctx.MallocFailed)
goto delete_from_cleanup;
Debug.Assert(tabList.Srcs == 1);
// Locate the table which we want to delete. This table has to be put in an SrcList structure because some of the subroutines we
// will be calling are designed to work with multiple tables and expect an SrcList* parameter instead of just a Table* parameter.
Table table = SrcList.Lookup(parse, tabList); // The table from which records will be deleted
if (table == null) goto delete_from_cleanup;
// Figure out if we have any triggers and if the table being deleted from is a view
#if !OMIT_TRIGGER
int dummy;
Trigger trigger = Triggers.Exist(parse, table, TK.DELETE, null, out dummy); // List of table triggers, if required
#if OMIT_VIEW
const bool isView = false;
#else
bool isView = (table.Select != null); // True if attempting to delete from a view
#endif
#else
const Trigger trigger = null;
bool isView = false;
#endif
// If pTab is really a view, make sure it has been initialized.
if (sqlite3ViewGetColumnNames(parse, table) != null || IsReadOnly(parse, table, (trigger != null)))
goto delete_from_cleanup;
int db = sqlite3SchemaToIndex(ctx, table.Schema); // Database number
Debug.Assert(db < ctx.DBs.length);
string dbName = ctx.DBs[db].Name; // Name of database holding pTab
ARC rcauth = Auth.Check(parse, AUTH.DELETE, table.Name, 0, dbName); // Value returned by authorization callback
Debug.Assert(rcauth == ARC.OK || rcauth == ARC.DENY || rcauth == ARC.IGNORE);
if (rcauth == ARC.DENY)
goto delete_from_cleanup;
Debug.Assert(!isView || trigger != null);
// Assign cursor number to the table and all its indices.
Debug.Assert(tabList.Srcs == 1);
int curId = tabList.Ids[0].Cursor = parse.Tabs++; // VDBE VdbeCursor number for pTab
Index idx; // For looping over indices of the table
for (idx = table.Index; idx != null; idx = idx.Next)
parse.Tabs++;
// Start the view context
if (isView)
Auth.ContextPush(parse, sContext, table.Name);
// Begin generating code.
Vdbe v = parse.GetVdbe(); // The virtual database engine
if (v == null)
goto delete_from_cleanup;
if (parse.Nested == 0) v.CountChanges();
parse.BeginWriteOperation(1, db);
// If we are trying to delete from a view, realize that view into a ephemeral table.
#if !OMIT_VIEW && !OMIT_TRIGGER
if (isView)
MaterializeView(parse, table, where_, curId);
#endif
// Resolve the column names in the WHERE clause.
NameContext sNC = new NameContext(); // Name context to resolve expressions in
sNC.Parse = parse;
sNC.SrcList = tabList;
if (sqlite3ResolveExprNames(sNC, ref where_) != 0)
goto delete_from_cleanup;
// Initialize the counter of the number of rows deleted, if we are counting rows.
int memCnt = -1; // Memory cell used for change counting
if ((ctx.Flags & Context.FLAG.CountRows) != 0)
{
memCnt = ++parse.Mems;
v.AddOp2(OP.Integer, 0, memCnt);
}
#if !OMIT_TRUNCATE_OPTIMIZATION
// Special case: A DELETE without a WHERE clause deletes everything. It is easier just to erase the whole table. Prior to version 3.6.5,
// this optimization caused the row change count (the value returned by API function sqlite3_count_changes) to be set incorrectly.
if (rcauth == ARC.OK && where_ == null && trigger == null && !IsVirtual(table) && !FKey.FkRequired(parse, table, null, 0))
{
Debug.Assert(!isView);
v.AddOp4(OP.Clear, table.Id, db, memCnt, table.Name, Vdbe.P4T.STATIC);
for (idx = table.Index; idx != null; idx = idx.Next)
{
Debug.Assert(idx.Schema == table.Schema);
v.AddOp2(OP.Clear, idx.Id, db);
}
}
else
#endif
// The usual case: There is a WHERE clause so we have to scan through the table and pick which records to delete.
{
int rowSet = ++parse.Mems; // Register for rowset of rows to delete
int rowid = ++parse.Mems; // Used for storing rowid values.
// Collect rowids of every row to be deleted.
v.AddOp2(OP.Null, 0, rowSet);
ExprList dummy = null;
WhereInfo winfo = Where.Begin(parse, tabList, where_, ref dummy, WHERE_DUPLICATES_OK, 0); // Information about the WHERE clause
if (winfo == null) goto delete_from_cleanup;
int regRowid = Expr.CodeGetColumn(parse, table, -1, curId, rowid); // Actual register containing rowids
v.AddOp2(OP.RowSetAdd, rowSet, regRowid);
if ((ctx.Flags & Context.FLAG.CountRows) != 0)
v.AddOp2(OP.AddImm, memCnt, 1);
Where.End(winfo);
// Delete every item whose key was written to the list during the database scan. We have to delete items after the scan is complete
// because deleting an item can change the scan order.
int end = v.MakeLabel();
// Unless this is a view, open cursors for the table we are deleting from and all its indices. If this is a view, then the
// only effect this statement has is to fire the INSTEAD OF triggers.
if (!isView)
sqlite3OpenTableAndIndices(parse, table, curId, OP.OpenWrite);
int addr = v.AddOp3(OP.RowSetRead, rowSet, end, rowid);
// Delete the row
#if !OMIT_VIRTUALTABLE
if (IsVirtual(table))
{
VTable vtable = VTable.GetVTable(ctx, table);
VTable.MakeWritable(parse, table);
v.AddOp4(OP.VUpdate, 0, 1, rowid, vtable, Vdbe.P4T.VTAB);
v.ChangeP5(OE.Abort);
sqlite3MayAbort(parse);
}
else
#endif
{
int count = (parse.Nested == 0; // True to count changes
GenerateRowDelete(parse, table, curId, rowid, count, trigger, OE.Default);
}
// End of the delete loop
v.AddOp2(OP.Goto, 0, addr);
v.ResolveLabel(end);
// Close the cursors open on the table and its indexes.
if (!isView && !IsVirtual(table))
{
for (int i = 1, idx = table.Index; idx != null; i++, idx = idx.Next)
v.AddOp2(OP.Close, curId + i, idx.Id);
v.AddOp1(OP.Close, curId);
}
}
// Update the sqlite_sequence table by storing the content of the maximum rowid counter values recorded while inserting into
// autoincrement tables.
if (parse.Nested == 0 && parse.TriggerTab == null)
sqlite3AutoincrementEnd(parse);
// Return the number of rows that were deleted. If this routine is generating code because of a call to sqlite3NestedParse(), do not
// invoke the callback function.
if ((ctx.Flags & Context.FLAG.CountRows) != 0 && parse.Nested == 0 && parse.TriggerTab == null)
{
v.AddOp2(OP.ResultRow, memCnt, 1);
v.SetNumCols(1);
v.SetColName(0, COLNAME_NAME, "rows deleted", SQLITE_STATIC);
}
delete_from_cleanup:
Auth.ContextPop(sContext);
SrcList.Delete(ctx, ref tabList);
Expr.Delete(ctx, ref where_);
return;
}