First pass at more advanced queries

Build a query with a table. Add wheres and limits. Then build it.

In future passes I want to make things more flexible. Also need to
figure out where escaping values should go.

spec/lucky_record/query_spec.cr

@@ -0,0 +1,41 @@
+require "../spec_helper"
+
+describe "LuckyRecord::Query" do
+  it "selects all" do
+    new_query.to_sql.should eq "SELECT * FROM users"
+  end
+
+  it "can be limited" do
+    query = new_query.limit(1)
+    query.to_sql.should eq "SELECT * FROM users LIMIT 1"
+  end
+
+  it "handles simple where comparison" do
+    query = new_query.where_eq(:name, "'Paul'")
+    query.to_sql.should eq "SELECT * FROM users WHERE name = 'Paul'"
+  end
+
+  it "handles >" do
+    query = new_query.where_gt(:age, 20)
+    query.to_sql.should eq "SELECT * FROM users WHERE age > 20"
+  end
+
+  it "handles >=" do
+    query = new_query.where_gte(:age, 20)
+    query.to_sql.should eq "SELECT * FROM users WHERE age >= 20"
+  end
+
+  it "handles <" do
+    query = new_query.where_lt(:age, 20)
+    query.to_sql.should eq "SELECT * FROM users WHERE age < 20"
+  end
+
+  it "handles <=" do
+    query = new_query.where_lte(:age, 20)
+    query.to_sql.should eq "SELECT * FROM users WHERE age <= 20"
+  end
+end
+
+private def new_query
+  LuckyRecord::Query.new(table: :users)
+end

src/lucky_record/query.cr

@@ -0,0 +1,62 @@
+class LuckyRecord::Query
+  private getter :table
+  @limit : Int32?
+  @wheres = [] of String
+
+  def initialize(@table : Symbol)
+  end
+
+  def to_sql
+    sql_clauses.reject do |clause|
+      clause.nil? || clause.blank?
+    end.join(" ")
+  end
+
+  private def sql_clauses
+    [select_sql, wheres_sql, limit_sql]
+  end
+
+  private def select_sql
+    "SELECT * FROM #{table}"
+  end
+
+  def limit(amount)
+    @limit = amount
+    self
+  end
+
+  private def limit_sql
+    if @limit
+      "LIMIT #{@limit}"
+    end
+  end
+
+  def where_eq(column, value)
+    @wheres << "WHERE #{column} = #{value}"
+    self
+  end
+
+  def where_gt(column, value)
+    @wheres << "WHERE #{column} > #{value}"
+    self
+  end
+
+  def where_gte(column, value)
+    @wheres << "WHERE #{column} >= #{value}"
+    self
+  end
+
+  def where_lt(column, value)
+    @wheres << "WHERE #{column} < #{value}"
+    self
+  end
+
+  def where_lte(column, value)
+    @wheres << "WHERE #{column} <= #{value}"
+    self
+  end
+
+  private def wheres_sql
+    @wheres.join(" ")
+  end
+end