1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #ifndef SQL_STATEMENT_H_
6 #define SQL_STATEMENT_H_
11 #include "base/basictypes.h"
12 #include "base/memory/ref_counted.h"
13 #include "base/strings/string16.h"
14 #include "sql/connection.h"
15 #include "sql/sql_export.h"
19 // Possible return values from ColumnType in a statement. These should match
20 // the values in sqlite3.h.
22 COLUMN_TYPE_INTEGER = 1,
23 COLUMN_TYPE_FLOAT = 2,
30 // sql::Statement s(connection_.GetUniqueStatement(...));
33 // return s.ColumnString(0);
35 // If there are errors getting the statement, the statement will be inert; no
36 // mutating or database-access methods will work. If you need to check for
41 // Step() and Run() just return true to signal success. If you want to handle
42 // specific errors such as database corruption, install an error handler in
43 // in the connection object using set_error_delegate().
44 class SQL_EXPORT Statement {
46 // Creates an uninitialized statement. The statement will be invalid until
47 // you initialize it via Assign.
50 explicit Statement(scoped_refptr<Connection::StatementRef> ref);
53 // Initializes this object with the given statement, which may or may not
54 // be valid. Use is_valid() to check if it's OK.
55 void Assign(scoped_refptr<Connection::StatementRef> ref);
57 // Resets the statement to an uninitialized state corrosponding to
58 // the default constructor, releasing the StatementRef.
61 // Returns true if the statement can be executed. All functions can still
62 // be used if the statement is invalid, but they will return failure or some
63 // default value. This is because the statement can become invalid in the
64 // middle of executing a command if there is a serious error and the database
66 bool is_valid() const { return ref_->is_valid(); }
68 // Running -------------------------------------------------------------------
70 // Executes the statement, returning true on success. This is like Step but
71 // for when there is no output, like an INSERT statement.
74 // Executes the statement, returning true if there is a row of data returned.
75 // You can keep calling Step() until it returns false to iterate through all
76 // the rows in your result set.
78 // When Step returns false, the result is either that there is no more data
79 // or there is an error. This makes it most convenient for loop usage. If you
80 // need to disambiguate these cases, use Succeeded().
86 // return s.Succeeded();
89 // Resets the statement to its initial condition. This includes any current
90 // result row, and also the bound variables if the |clear_bound_vars| is true.
91 void Reset(bool clear_bound_vars);
93 // Returns true if the last executed thing in this statement succeeded. If
94 // there was no last executed thing or the statement is invalid, this will
96 bool Succeeded() const;
98 // Binding -------------------------------------------------------------------
100 // These all take a 0-based argument index and return true on success. You
101 // may not always care about the return value (they'll DCHECK if they fail).
102 // The main thing you may want to check is when binding large blobs or
103 // strings there may be out of memory.
104 bool BindNull(int col);
105 bool BindBool(int col, bool val);
106 bool BindInt(int col, int val);
107 bool BindInt64(int col, int64 val);
108 bool BindDouble(int col, double val);
109 bool BindCString(int col, const char* val);
110 bool BindString(int col, const std::string& val);
111 bool BindString16(int col, const base::string16& value);
112 bool BindBlob(int col, const void* value, int value_len);
114 // Retrieving ----------------------------------------------------------------
116 // Returns the number of output columns in the result.
117 int ColumnCount() const;
119 // Returns the type associated with the given column.
121 // Watch out: the type may be undefined if you've done something to cause a
122 // "type conversion." This means requesting the value of a column of a type
123 // where that type is not the native type. For safety, call ColumnType only
124 // on a column before getting the value out in any way.
125 ColType ColumnType(int col) const;
126 ColType DeclaredColumnType(int col) const;
128 // These all take a 0-based argument index.
129 bool ColumnBool(int col) const;
130 int ColumnInt(int col) const;
131 int64 ColumnInt64(int col) const;
132 double ColumnDouble(int col) const;
133 std::string ColumnString(int col) const;
134 base::string16 ColumnString16(int col) const;
136 // When reading a blob, you can get a raw pointer to the underlying data,
137 // along with the length, or you can just ask us to copy the blob into a
138 // vector. Danger! ColumnBlob may return NULL if there is no data!
139 int ColumnByteLength(int col) const;
140 const void* ColumnBlob(int col) const;
141 bool ColumnBlobAsString(int col, std::string* blob);
142 bool ColumnBlobAsString16(int col, base::string16* val) const;
143 bool ColumnBlobAsVector(int col, std::vector<char>* val) const;
144 bool ColumnBlobAsVector(int col, std::vector<unsigned char>* val) const;
146 // Diagnostics --------------------------------------------------------------
148 // Returns the original text of sql statement. Do not keep a pointer to it.
149 const char* GetSQLStatement();
152 // This is intended to check for serious errors and report them to the
153 // connection object. It takes a sqlite error code, and returns the same
154 // code. Currently this function just updates the succeeded flag, but will be
155 // enhanced in the future to do the notification.
156 int CheckError(int err);
158 // Contraction for checking an error code against SQLITE_OK. Does not set the
160 bool CheckOk(int err) const;
162 // Should be called by all mutating methods to check that the statement is
163 // valid. Returns true if the statement is valid. DCHECKS and returns false
165 // The reason for this is to handle two specific cases in which a Statement
166 // may be invalid. The first case is that the programmer made an SQL error.
167 // Those cases need to be DCHECKed so that we are guaranteed to find them
168 // before release. The second case is that the computer has an error (probably
169 // out of disk space) which is prohibiting the correct operation of the
170 // database. Our testing apparatus should not exhibit this defect, but release
171 // situations may. Therefore, the code is handling disjoint situations in
172 // release and test. In test, we're ensuring correct SQL. In release, we're
173 // ensuring that contracts are honored in error edge cases.
174 bool CheckValid() const;
176 // The actual sqlite statement. This may be unique to us, or it may be cached
177 // by the connection, which is why it's refcounted. This pointer is
178 // guaranteed non-NULL.
179 scoped_refptr<Connection::StatementRef> ref_;
181 // Set after Step() or Run() are called, reset by Reset(). Used to
182 // prevent accidental calls to API functions which would not work
183 // correctly after stepping has started.
186 // See Succeeded() for what this holds.
189 DISALLOW_COPY_AND_ASSIGN(Statement);
194 #endif // SQL_STATEMENT_H_