Added Arg() for generating the argument placeholder for use in the query

README.md

@@ -1,19 +1,16 @@
 # sqeasy
 [![PkgGoDev](https://pkg.go.dev/badge/github.com/ferdypruis/sqeasy)](https://pkg.go.dev/github.com/ferdypruis/sqeasy)
 
-Attempting to make usage of Go's `sql`-package easier to maintain, by preventing you to manually have to 
-count and match columns and variables.
-
-## Features
-* Map columns to destination values
-* Use named parameters
+Small wrappers to make usage of Go's `sql`-package with a CockroachDB database easier to maintain, by for example
+mapping variables to positional arguments.
 
 ## Examples
 ### Map columns to destination values
+Instead of summing all destination variables in `Scan()`, map the columns onto your variables with `sqeasy.SelectColumns`
+and have them scanned into them.
 ```go
 var db *sql.DB
 
-
 var (
     colA      string
     timestamp time.Time
@@ -31,15 +28,29 @@ err := columns.Scan(row)
 ```
 
 ### Use named parameters
+Instead of the $1, $2, $3 etc positional parameters in your queries, use named ones. Bind values to the names 
+using `sqeasy.NamedParams`.
 ```go
 var db *sql.DB
 
+params := sqeasy.NamedParams{
+    {"colA",      "notthis"},
+    {"timestamp", time.Now()},
+}
+
+query := "SELECT * FROM table WHERE a_column != :colA AND timestamp < :timestamp"
+row := sqeasy.QueryRow(db, query, params)
+```
+
+The same `sqeasy.NamedParams` could be used to for example generate INSERT statements.
+```go
+var db *sql.DB
 
 params := sqeasy.NamedParams{
-    "colA":      "notthis",
+    "a_column":  "this",
     "timestamp": time.Now(),
 }
 
-query := "SELECT * FROM table WHERE a_column != :colA AND timestamp < :timestamp"
+query := "INSERT INTO table (" + params.ExprList() + ") VALUES (" + params.Params() + ")"
 row := sqeasy.QueryRow(db, query, params)
 ```

arg.go

@@ -0,0 +1,11 @@
+package sqeasy
+
+import (
+	"strconv"
+)
+
+// Arg adds a value to args, returning it's position
+func Arg(args *[]interface{}, arg interface{}) string {
+	*args = append(*args, arg)
+	return `$` + strconv.Itoa(len(*args))
+}

arg_test.go

@@ -0,0 +1,15 @@
+package sqeasy
+
+import (
+	"database/sql"
+	"time"
+)
+
+func ExampleArg() {
+	var db *sql.DB
+
+	var args []interface{}
+	query := `SELECT * FROM table WHERE a_column = ` + Arg(&args, `fubar`) + ` AND timestamp < ` + Arg(&args, time.Now())
+
+	_ = db.QueryRow(query, args...)
+}

named.go

@@ -15,7 +15,7 @@ func (np NamedParams) Parse(query string) (string, []interface{}, error) {
 	return query, args, err
 }
 
-// Args returns the value for each parameter on the position as indicated in the param slice
+// args returns the value for each parameter on the position as indicated in the param slice
 func (np NamedParams) Args(params []string) ([]interface{}, error) {
 	args := make([]interface{}, len(params))
 

named_test.go

@@ -2,8 +2,9 @@ package sqeasy_test
 
 import (
 	"database/sql"
-	"github.com/ferdypruis/sqeasy"
 	"time"
+
+	"github.com/ferdypruis/sqeasy"
 )
 
 func ExampleNamedParams() {
@@ -15,5 +16,5 @@ func ExampleNamedParams() {
 	}
 
 	query := "SELECT * FROM table WHERE a_column != :colA AND timestamp < :timestamp"
-	row := sqeasy.QueryRow(db, query, params)
+	_ = sqeasy.QueryRow(db, query, params)
 }

select_test.go

@@ -2,6 +2,7 @@ package sqeasy_test
 
 import (
 	"database/sql"
+
 	"github.com/ferdypruis/sqeasy"
 )
 
@@ -21,5 +22,5 @@ func ExampleSelectColumns() {
 	}
 
 	row := db.QueryRow("SELECT " + columns.ExprList() + " FROM table")
-	err := columns.Scan(row)
+	_ = columns.Scan(row)
 }