func ExtractParameters(h api.SQLHSTMT) ([]Parameter, error) {
// count parameters
var n, nullable api.SQLSMALLINT
ret := api.SQLNumParams(h, &n)
if IsError(ret) {
return nil, NewError("SQLNumParams", h)
}
if n <= 0 {
// no parameters
return nil, nil
}
ps := make([]Parameter, n)
// fetch param descriptions
for i := range ps {
p := &ps[i]
ret = api.SQLDescribeParam(h, api.SQLUSMALLINT(i+1),
&p.SQLType, &p.Size, &p.Decimal, &nullable)
if IsError(ret) {
// SQLDescribeParam is not implemented by freedts,
// it even fails for some statements on windows.
// Will try request without these descriptions
continue
}
p.isDescribed = true
}
return ps, nil
}
func describeColumn(h api.SQLHSTMT, idx int, namebuf []uint16) (namelen int, sqltype api.SQLSMALLINT, size api.SQLULEN, ret api.SQLRETURN) {
var l, decimal, nullable api.SQLSMALLINT
ret = api.SQLDescribeCol(h, api.SQLUSMALLINT(idx+1),
(*api.SQLWCHAR)(unsafe.Pointer(&namebuf[0])),
api.SQLSMALLINT(len(namebuf)), &l,
&sqltype, &size, &decimal, &nullable)
return int(l), sqltype, size, ret
}
func (l *BufferLen) Bind(h api.SQLHSTMT, idx int, ctype api.SQLSMALLINT, buf []byte) api.SQLRETURN {
return api.SQLBindCol(h, api.SQLUSMALLINT(idx+1), ctype,
api.SQLPOINTER(unsafe.Pointer(&buf[0])), api.SQLLEN(len(buf)),
(*api.SQLLEN)(l))
}
func (p *Parameter) BindValue(h api.SQLHSTMT, idx int, v driver.Value) error {
// TODO(brainman): Reuse memory for previously bound values. If memory
// is reused, we, probably, do not need to call SQLBindParameter either.
var ctype, sqltype, decimal api.SQLSMALLINT
var size api.SQLULEN
var buflen api.SQLLEN
var plen *api.SQLLEN
var buf unsafe.Pointer
switch d := v.(type) {
case nil:
ctype = api.SQL_C_WCHAR
p.Data = nil
buf = nil
size = 1
buflen = 0
plen = p.StoreStrLen_or_IndPtr(api.SQL_NULL_DATA)
sqltype = api.SQL_WCHAR
case string:
ctype = api.SQL_C_WCHAR
b := api.StringToUTF16(d)
p.Data = b
buf = unsafe.Pointer(&b[0])
l := len(b)
l -= 1 // remove terminating 0
size = api.SQLULEN(l)
if size < 1 {
// size cannot be less then 1 even for empty fields
size = 1
}
l *= 2 // every char takes 2 bytes
buflen = api.SQLLEN(l)
plen = p.StoreStrLen_or_IndPtr(buflen)
if p.isDescribed {
// only so we can handle very long (>4000 chars) parameters
sqltype = p.SQLType
} else {
sqltype = api.SQL_WCHAR
}
case int64:
ctype = api.SQL_C_SBIGINT
p.Data = &d
buf = unsafe.Pointer(&d)
sqltype = api.SQL_BIGINT
size = 8
case bool:
var b byte
if d {
b = 1
}
ctype = api.SQL_C_BIT
p.Data = &b
buf = unsafe.Pointer(&b)
sqltype = api.SQL_BIT
size = 1
case float64:
ctype = api.SQL_C_DOUBLE
p.Data = &d
buf = unsafe.Pointer(&d)
sqltype = api.SQL_DOUBLE
size = 8
case time.Time:
ctype = api.SQL_C_TYPE_TIMESTAMP
y, m, day := d.Date()
b := api.SQL_TIMESTAMP_STRUCT{
Year: api.SQLSMALLINT(y),
Month: api.SQLUSMALLINT(m),
Day: api.SQLUSMALLINT(day),
Hour: api.SQLUSMALLINT(d.Hour()),
Minute: api.SQLUSMALLINT(d.Minute()),
Second: api.SQLUSMALLINT(d.Second()),
Fraction: api.SQLUINTEGER(d.Nanosecond()),
}
p.Data = &b
buf = unsafe.Pointer(&b)
sqltype = api.SQL_TYPE_TIMESTAMP
if p.isDescribed && p.SQLType == api.SQL_TYPE_TIMESTAMP {
decimal = p.Decimal
}
if decimal <= 0 {
// represented as yyyy-mm-dd hh:mm:ss.fff format in ms sql server
decimal = 3
}
size = 20 + api.SQLULEN(decimal)
case []byte:
ctype = api.SQL_C_BINARY
b := make([]byte, len(d))
copy(b, d)
p.Data = b
buf = unsafe.Pointer(&b[0])
buflen = api.SQLLEN(len(b))
plen = p.StoreStrLen_or_IndPtr(buflen)
size = api.SQLULEN(len(b))
sqltype = api.SQL_BINARY
default:
panic(fmt.Errorf("unsupported type %T", v))
}
ret := api.SQLBindParameter(h, api.SQLUSMALLINT(idx+1),
api.SQL_PARAM_INPUT, ctype, sqltype, size, decimal,
api.SQLPOINTER(buf), buflen, plen)
if IsError(ret) {
return NewError("SQLBindParameter", h)
}
return nil
}