FireDAC 下的 Sqlite [4] - 创建数据库

建立数据库的代码:


{建立内存数据库的一般代码:}
begin
FDConnection1.DriverName := 'SQLite'; //同 FDConnection1.Params.Add('DriverID=SQLite');
// FDConnection1.Params.Add('Database=:memory:'); //可省略这行, FireDAC 的源码显示, if Database = '' then Database := ':memory:';
// FDConnection1.Params.Add('SQLiteAdvanced=page_size=4096'); //可指定内存页大小, 这是默认值
FDConnection1.Connected := True;
end {建立文件数据库的一般代码:}
begin
FDConnection1.Params.Add('DriverID=SQLite');
FDConnection1.Params.Add('Database=C:\Temp\New1.sdb'); //如果文件存在就打开, 不存在就建立
// FDConnection1.Params.Add('SQLiteAdvanced=temp_store=Memory'); //可强制临时文件在内存以提高效率. 0:DEFAULT; 1:FILE; 2:MEMORY
// FDConnection1.Params.Add('SQLiteAdvanced=temp_store_directory=C:\Temp'); //默认的临时文件路径应该是 C:\Documents and Settings\user-name\Local Settings\Temp\
// FDConnection1.Params.Add('OpenMode=CreateUTF8'); //默认是 CreateUTF8, 也可选择 CreateUTF16
// FDConnection1.Params.Add('LockingMode=Normal'); //默认是多用户模式, 如果使用独占模式 LockingMod=Exclusive 会更有效率
FDConnection1.Connected := True;
end;

所有建立参数参见: http://www.sqlite.org/pragma.html

先在空白窗体上添加: TFDConnection、TFDPhysSQLiteDriverLink、TFDGUIxWaitCursor; 数据库的建立主要通过 TFDConnection 完成.

同时添加用于呈现数据的 TFDQuery、TDataSource、TDBGrid, 还要添加一个 TFDCommand 用于提交建表命令, 然后调整如下属性:

FDQuery1    . Connection = FDConnection1
DataSource1 . DataSet = FDQuery1
DBGrid1 . DataSource = DataSource1
FDCommand1 . Connection = FDConnection1

你可以复制下面文本框中的内容, 然后直接往窗体上贴, 以快速完成以上的添加过程:

object FDConnection1: TFDConnection
Left = 34
Top = 24
end
object FDPhysSQLiteDriverLink1: TFDPhysSQLiteDriverLink
Left = 143
Top = 24
end
object FDGUIxWaitCursor1: TFDGUIxWaitCursor
Provider = 'Forms'
Left = 260
Top = 24
end
object FDQuery1: TFDQuery
Connection = FDConnection1
Left = 32
Top = 80
end
object DataSource1: TDataSource
DataSet = FDQuery1
Left = 148
Top = 80
end
object FDCommand1: TFDCommand
Connection = FDConnection1
Left = 264
Top = 88
end
object DBGrid1: TDBGrid
Left = 24
Top = 144
Width = 409
Height = 137
DataSource = DataSource1
TabOrder = 0
TitleFont.Charset = DEFAULT_CHARSET
TitleFont.Color = clWindowText
TitleFont.Height = -11
TitleFont.Name = 'Tahoma'
TitleFont.Style = []
end


测试代码:


procedure TForm1.FormCreate(Sender: TObject);
const
dbPath = 'C:\Temp\SQLiteTest.sdb';
begin
if FileExists(dbPath) then DeleteFile(dbPath); with FDConnection1 do begin
Params.Add('DriverID=SQLite');
Params.Add('Database=' + dbPath);
Connected := True;
end; {创建一个名为 MyTable 的表, 字段包括: ID, Name, Age, Note, Picture}
with FDCommand1.CommandText do begin
Add('CREATE TABLE MyTable(');
Add('ID integer PRIMARY KEY,'); //Integer 类型, 同时设为主键
Add('Name string(10),'); //能容下 10 个字符的 String 类型
Add('Age byte,'); //Byte 类型
Add('Note text,'); //Memo 类型
Add('Picture blob'); //Blob(二进制)类型
Add(')');
end;
FDCommand1.Active := True; {查看表}
FDQuery1.Open('SELECT * FROM MyTable');
end;

效果图:
FireDAC 下的 Sqlite [4] - 创建数据库


直接使用 TFDConnection 提交 DDL 命令更简单:


procedure TForm1.FormCreate(Sender: TObject);
const
dbPath = 'C:\Temp\SQLiteTest.sdb';
begin
if FileExists(dbPath) then DeleteFile(dbPath); with FDConnection1 do begin
Params.Add('DriverID=SQLite');
Params.Add('Database=' + dbPath);
Connected := True;
end; {创建一个名为 MyTable 的表, 字段包括: ID, Name, Age, Note, Picture}
FDConnection1.ExecSQL('CREATE TABLE MyTable(ID integer PRIMARY KEY, Name string(10), Age byte, Note text, Picture blob)'); {查看表}
FDQuery1.Open('SELECT * FROM MyTable');
end;

使用 SQLite 底层包装完成的建表提交(这样应该更有效率):


uses FireDAC.Phys.SQLiteWrapper; //为使用 TSQLiteStatement

{使用 TSQLiteStatement 完成的提交 SQL 命令的函数}
procedure MyExecSQL(ACon: TFDConnection; const ASQL: String);
begin
with TSQLiteStatement.Create(ACon.CliObj) do
try
Prepare(ASQL);
Execute;
while PrepareNextCommand do Execute;
finally
Free;
end;
end; procedure TForm1.FormCreate(Sender: TObject);
const
dbPath = 'C:\Temp\SQLiteTest.sdb';
begin
if FileExists(dbPath) then DeleteFile(dbPath); with FDConnection1 do begin
Params.Add('DriverID=SQLite');
Params.Add('Database=' + dbPath);
Connected := True;
end; {创建一个名为 MyTable 的表, 字段包括: ID, Name, Age, Note, Picture}
MyExecSQL(FDConnection1, 'CREATE TABLE MyTable(ID integer PRIMARY KEY, Name string(10), Age byte, Note text, Picture blob)'); {查看表}
FDQuery1.Open('SELECT * FROM MyTable');
end;

关于数据类型, SQLite 本身只支持(Null, Integer, Real, Text, Blob), 但我们可以放心使用 Delphi 的大多数类型(也包括 Delphi 没有的), 因为 FireDAC 幕后做了转换工作.

SQLite 到 FireDAC 数据类型映射表: (http://docwiki.embarcadero.com/RADStudio/XE6/en/Using_SQLite_with_FireDAC)

Type name Description
rowid | _rowid_ | oid dtInt64, Attrs = [caSearchable, caAllowNull, caROWID]
bit | bool | boolean | logical | yesno dtBoolean
tinyint | shortint | int8 [unsigned] dtSByte / dtByte
byte | uint8 dtByte
smallint | int16 [unsigned] dtInt16 / dtUInt16
word | uint16 | year dtUInt16
mediumint | integer | int | int32 [unsigned] dtInt32 / dtUInt32
longword | uint32 dtUInt32
bigint | int64 | counter | autoincrement | identity [unsigned] dtInt64 / dtUInt64
longlongword | uint64 dtUInt64
real | float | double dtDouble
single [precision] [(p, s)] dtSingle / dtBCD / dtFmtBCD
decimal | dec | numeric | number [unsigned] [(p, s)] dtSByte / dtInt16 / dtInt32 / dtInt64

dtByte / dtUInt16 / dtUInt32 / dtUInt64

dtBCD / dtFmtBCD
money | smallmoney | currency | financial [(p, s)] dtCurrency
date | smalldate dtDate
datetime | smalldatetime dtDateTime
timestamp dtDateTimeStamp
time dtTime
char | character [(l)] dtAnsiString, Len = L, Attrs = [caFixedLen]
varchar | varchar2 | tynitext | character varying | char varying [(l)] dtAnsiString, Len = L
nchar | national char | national character [(l)] dtWideString, Len = L, Attrs = [caFixedLen]
nvarchar | nvarchar2 | national char varying | string [(l)] dtWideString, Len = L
raw | tyniblob | varbinary | binary | binary varying [(l)] dtByteString, Len = L
blob | mediumblob | image | longblob | long binary | long raw | longvarbinary | general | oleobject | tinyblob dtBlob
mediumtext | longtext | clob | memo | note | long | long text | longchar | longvarchar | tinytext dtMemo
text | ntext | wtext | nclob | nmemo | long ntext | long wtext | national text | longwchar | longwvarchar | html dtWideMemo
xmldata | xmltype | xml dtXML
guid | uniqueidentifier dtGUID
other data types dtWideString
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