sdk/hints: adapt sqlite to also support postgres.

sdk/hints/sqlh/interop.go

@@ -0,0 +1,48 @@
+package sqlh
+
+import (
+	"strconv"
+	"strings"
+)
+
+type interop struct {
+	maxFunc              string
+	getUnixEpochFunc     string
+	generateBindingSpots func(start, n int) string
+}
+
+var sqliteInterop = interop{
+	maxFunc:          "max",
+	getUnixEpochFunc: "unixepoch()",
+	generateBindingSpots: func(_, n int) string {
+		b := strings.Builder{}
+		b.Grow(n * 2)
+		for i := range n {
+			if i == n-1 {
+				b.WriteString("?")
+			} else {
+				b.WriteString("?,")
+			}
+		}
+		return b.String()
+	},
+}
+
+var postgresInterop = interop{
+	maxFunc:          "greatest",
+	getUnixEpochFunc: "extract(epoch from now())",
+	generateBindingSpots: func(start, n int) string {
+		b := strings.Builder{}
+		b.Grow(n * 2)
+		end := start + n
+		for i := start; i < end; i++ {
+			v := i + 1
+			b.WriteRune('$')
+			b.WriteString(strconv.Itoa(v))
+			if i != end-1 {
+				b.WriteRune(',')
+			}
+		}
+		return b.String()
+	},
+}