Fortran 2018接口绑定到SQLite 3的集合

# fortran-sqlite3 A work-in-progress collection of Fortran 2018 interface bindings to SQLite 3. ## Build Instructions Make sure that `libsqlite3` is installed with development headers. On FreeBSD, run: ``` # pkg install databases/sqlite3 ``` Then, clone the GitHub repository: ``` $ git clone https://github.com/interkosmos/fortran-sqlite3 $ cd fortran-sqlite3/ ``` Either build the library with `fpm` or `make`. Once compiled, link your Fortran application against `libfortran-sqlite3.a` and `-lsqlite3`. ### fpm Simply execute the Fortran Package Manager: ``` $ fpm build --profile=release ``` The output files are written to `build/`. ### make Execute the provided `Makefile` with `make`: ``` $ make ``` You may want to override the default Fortran compiler (GNU Fortran) by passing the `FC` argument, for instance: ``` $ make FC=ifort ``` ## Example The following SQL schema will be created by the example: ```sql CREATE TABLE example_table ( id INTEGER PRIMARY KEY, string VARCHAR(32), value INTEGER ); ``` The program opens a database `example.db`, creates the table `example_table`, inserts some values, then reads them back in, and prints them to console. The module `sqlite_util` contains C interoperability functions/interfaces to convert C char pointer to Fortran allocatable character. ```fortran ! example.f90 program example use, intrinsic :: iso_c_binding use :: sqlite use :: sqlite_util implicit none (type, external) character(len=:), allocatable :: errmsg integer :: rc type(c_ptr) :: db type(c_ptr) :: stmt ! Open SQLite database. rc = sqlite3_open('example.db', db) ! Create table. rc = sqlite3_exec(db, "CREATE TABLE example_table (" // & "id INTEGER PRIMARY KEY," // & "string VARCHAR(32)," // & "value INTEGER)", c_null_ptr, c_null_ptr, errmsg) if (rc /= SQLITE_OK) print '("sqlite3_exec(): ", a)', errmsg ! Create a prepared statement. rc = sqlite3_prepare(db, "INSERT INTO example_table(string, value) VALUES(?, ?)", stmt) ! Bind the values to the statement. rc = sqlite3_bind_text(stmt, 1, 'one') rc = sqlite3_bind_int(stmt, 2, 12345) ! Run the statement. rc = sqlite3_step(stmt) if (rc /= SQLITE_DONE) print '("sqlite3_step(): failed")' ! Delete the statement. rc = sqlite3_finalize(stmt) ! Read values from database. rc = sqlite3_prepare(db, "SELECT * FROM example_table", stmt) ! Print rows line by line. do while (sqlite3_step(stmt) /= SQLITE_DONE) call print_values(stmt, 3) end do ! Delete the statement. rc = sqlite3_finalize(stmt) ! Close SQLite handle. rc = sqlite3_close(db) contains subroutine print_values(stmt, ncols) type(c_ptr), intent(inout) :: stmt integer, intent(in) :: ncols integer :: col_type integer :: i do i = 0, ncols - 1 col_type = sqlite3_column_type(stmt, i) select case (col_type) case (SQLITE_INTEGER) write (*, '(i12)', advance='no') sqlite3_column_int(stmt, i) case (SQLITE_FLOAT) write (*, '(f0.8)', advance='no') sqlite3_column_double(stmt, i) case (SQLITE_TEXT) write (*, '(a12)', advance='no') sqlite3_column_text(stmt, i) case default write (*, '(" unsupported")', advance='no') end select end do print * end subroutine print_values end program example ``` Compile, link, and run the example with: ``` $ gfortran -o example example.f90 libfortran-sqlite3.a -lsqlite3 $ ./example 1 one 12345 ``` ## fpm You can add *fortran-sqlite3* as an [fpm](https://github.com/fortran-lang/fpm) dependency: ```toml [dependencies] fortran-sqlite3 = { git = "https://github.com/interkosmos/fortran-sqlite3.git" } ``` ## Compatibility Note that the wrapper function `sqlite3_bind_text()` selects destructor type `SQLITE_TRANSIENT` if argument `destructor` is not passed, in contrast to the SQLite default `SQLITE_STATIC`. Therefore, SQLite will make a copy of the given value. Otherwise, the passed variable could go out of scope before SQLite was able to read the string completely, leading to possible data corruption. ## Licence ISC