### Database Schema:
CREATE TABLE partsupp (
	ps_partkey	INTEGER	NOT NULL	PRIMARY KEY,
	ps_suppkey	INTEGER	NOT NULL	PRIMARY KEY,
	ps_supplycost	REAL	NOT NULL,
	ps_availqty	INTEGER	NULL,
	ps_comment	TEXT	NULL,
	foreign key (ps_partkey) references part (p_partkey),
	foreign key (ps_suppkey) references supplier (s_suppkey)
);

CREATE TABLE orders (
	o_orderdate	DATE	NULL,
	o_orderkey	INTEGER	NOT NULL	PRIMARY KEY,
	o_custkey	INTEGER	NOT NULL,
	o_orderpriority	TEXT	NULL,
	o_shippriority	INTEGER	NULL,
	o_clerk	TEXT	NULL,
	o_orderstatus	TEXT	NULL,
	o_totalprice	REAL	NULL,
	o_comment	TEXT	NULL,
	foreign key (o_custkey) references customer (c_custkey)
);

CREATE TABLE supplier (
	s_suppkey	INTEGER	NOT NULL	PRIMARY KEY,
	s_nationkey	INTEGER	NULL,
	s_comment	TEXT	NULL,
	s_name	TEXT	NULL,
	s_address	TEXT	NULL,
	s_phone	TEXT	NULL,
	s_acctbal	REAL	NULL,
	foreign key (s_nationkey) references nation (n_nationkey)
);

CREATE TABLE lineitem (
	l_shipdate	DATE	NULL,
	l_orderkey	INTEGER	NOT NULL	PRIMARY KEY,
	l_discount	REAL	NOT NULL,
	l_extendedprice	REAL	NOT NULL,
	l_suppkey	INTEGER	NOT NULL,
	l_quantity	INTEGER	NOT NULL,
	l_returnflag	TEXT	NULL,
	l_partkey	INTEGER	NOT NULL,
	l_linestatus	TEXT	NULL,
	l_tax	REAL	NOT NULL,
	l_commitdate	DATE	NULL,
	l_receiptdate	DATE	NULL,
	l_shipmode	TEXT	NULL,
	l_linenumber	INTEGER	NOT NULL	PRIMARY KEY,
	l_shipinstruct	TEXT	NULL,
	l_comment	TEXT	NULL,
	foreign key (l_orderkey) references orders (o_orderkey),
	foreign key (l_partkey) references partsupp (ps_partkey),
	foreign key (l_suppkey) references partsupp (ps_suppkey)
);

CREATE TABLE part (
	p_partkey	INTEGER	NOT NULL	PRIMARY KEY,
	p_type	TEXT	NULL,
	p_size	INTEGER	NULL,
	p_brand	TEXT	NULL,
	p_name	TEXT	NULL,
	p_container	TEXT	NULL,
	p_mfgr	TEXT	NULL,
	p_retailprice	REAL	NULL,
	p_comment	TEXT	NULL
);

CREATE TABLE region (
	r_regionkey	INTEGER	NOT NULL	PRIMARY KEY,
	r_name	TEXT	NULL,
	r_comment	TEXT	NULL
);

CREATE TABLE nation (
	n_nationkey	INTEGER	NOT NULL	PRIMARY KEY,
	n_name	TEXT	NULL,
	n_regionkey	INTEGER	NULL,
	n_comment	TEXT	NULL,
	foreign key (n_regionkey) references region (r_regionkey)
);

CREATE TABLE customer (
	c_custkey	INTEGER	NOT NULL	PRIMARY KEY,
	c_mktsegment	TEXT	NULL	DEFAULT NULL,
	c_nationkey	INTEGER	NULL	DEFAULT NULL,
	c_name	TEXT	NULL	DEFAULT NULL,
	c_address	TEXT	NULL	DEFAULT NULL,
	c_phone	TEXT	NULL	DEFAULT NULL,
	c_acctbal	REAL	NULL	DEFAULT NULL,
	c_comment	TEXT	NULL	DEFAULT NULL,
	foreign key (c_nationkey) references nation (n_nationkey)
);

### User's Query:
To which segment belongs the customer that made the most orders in April 1994?

### Extra Knowledge:
segment refers to c_mktsegment; customer made the most orders in April 1994 refers to c_custkey where o_orderdate LIKE '1994-04-%' and MAX(COUNT(o_orderkey));
SELECT T.c_mktsegment FROM ( SELECT T2.c_mktsegment, COUNT(T1.o_orderkey) AS num FROM orders AS T1 INNER JOIN customer AS T2 ON T1.o_custkey = T2.c_custkey WHERE T1.o_orderdate LIKE '1994-04-%' GROUP BY T1.o_custkey ) AS T ORDER BY T.num DESC LIMIT 1