完成基本的sqlalchemy select无筛选的学习

s2_fetch_data.py

@@ -1,22 +1,73 @@
 from sqlalchemy import select
 from s1_models import *
 
-# 方法1
-s1 = select([cookies])  # 2.0废弃
-rp1 = connection.execute(s1)
-results1 = rp1.fetchall()
-print(results1)
-
-# 方法2
-s2 = cookies.select()
-str(s2)
-rp2 = connection.execute(s2)
-results2 = rp2.fetchall()
-print(results2)
-print(results2[0])
-first_row = results2[0]
-print(first_row[1])
-print(first_row.cookie_name)
-print(first_row[cookies.c.cookie_name])
-results3 = rp2.scalar()
+# 方法1 rp = ResultProxy
+# s1 = select([cookies])  # 2.0废弃
+# rp1 = connection.execute(s1)
+# results1 = rp1.fetchall()
+# print(results1)
+#
+# # 方法2
+# s2 = cookies.select()
+# str(s2)
+# rp2 = connection.execute(s2)
+# results2 = rp2.fetchall()
+# print(results2)
+# print(results2[0])
+# first_row = results2[0]
+# print(first_row[1])
+# print(first_row.cookie_name)
+# print(first_row[cookies.c.cookie_name])
+#
+
+# 添加查询参数
+s3 = select([cookies.c.cookie_name, cookies.c.quantity])
+rp3 = connection.execute(s3)
+print(rp3.keys())
+results3 = rp3.fetchall()
 print(results3)
+result_dict = [dict(zip(rp3.keys(), r)) for r in results3]
+print(result_dict)
+
+# 排序
+s4 = select([cookies.c.cookie_name, cookies.c.quantity]).order_by(cookies.c.quantity)
+rp4 = connection.execute(s4)
+for cookie in rp4:
+    print(f"{cookie.quantity} - {cookie.cookie_name}")
+
+# 反向排序
+from sqlalchemy import desc
+
+s5 = select([cookies.c.cookie_name, cookies.c.quantity]).order_by(desc(cookies.c.quantity))
+rp5 = connection.execute(s5)
+for cookie in rp5:
+    print(f"{cookie.quantity} - {cookie.cookie_name}")
+
+# limit
+s6 = select([cookies.c.cookie_name, cookies.c.quantity]).order_by(cookies.c.quantity).limit(2)
+rp6 = connection.execute(s6)
+for cookie in rp6:
+    print(f"{cookie.quantity} - {cookie.cookie_name}")
+
+# sum
+from sqlalchemy import func
+
+s7 = select([func.sum(cookies.c.quantity)])
+print(str(s7))
+rp7 = connection.execute(s7)
+print(rp7.scalar())
+
+
+# count
+s8 = select([func.count(cookies.c.cookie_name)])
+print(str(s8))
+rp8 = connection.execute(s8)
+print(rp8.scalar())
+
+
+# as
+s9 = select([func.count(cookies.c.cookie_name).label('cookie_count')])
+rp9 = connection.execute(s9)
+r = rp9.first()
+print(list(r.keys()))
+print(r.cookie_count)