MariaDB [fechas]> show databases;
+--------------------+
| Database           |
+--------------------+
| academico          |
| aplicacion_cadena  |
| comercial          |
| consulta_externa   |
| facturacion        |
| fechas             |
| fechas001          |
| information_schema |
| institucion        |
| institucion1       |
| libreria           |
| matricula2         |
| mysql              |
| performance_schema |
| phpmyadmin         |
| secundaria         |
| test               |
| urgencias          |
+--------------------+
18 rows in set (0.03 sec)

MariaDB [fechas]> show tables;
+------------------+
| Tables_in_fechas |
+------------------+
| estmat           |
| estudiante       |
| materia          |
| repaso2          |
+------------------+
4 rows in set (0.00 sec)

MariaDB [fechas]> select * from repaso2;
+--------+-------------------+--------+-----------------+----------+
| codigo | nombre            | sexo   | fechanacimiento | nrohijos |
+--------+-------------------+--------+-----------------+----------+
| 111222 | carlos ramirez    | hombre | 1969-04-04      |        2 |
| 333666 | marina ruiz       | mujer  | 1978-12-15      |        3 |
| 999111 | veronica gonzalez | mujer  | 1982-03-30      |        1 |
| 888777 | isabel betancur   | mujer  | 1977-11-15      |        1 |
| 333777 | gladys bermudez   | mujer  | 1979-01-01      |        2 |
| 444666 | sandra henao      | mujer  | 1982-11-25      |        3 |
| 555777 | mario gomez       | hombre | 1982-05-29      |        2 |
| 111333 | andrea gutierrez  | mujer  | 1985-04-12      |        1 |
| 444777 | carlos sepulveda  | hombre | 1974-01-10      |        1 |
| 555333 | fernando perez    | hombre | 1980-11-11      |        4 |
| 666555 | juliana arredondo | mujer  | 1988-12-31      |        2 |
+--------+-------------------+--------+-----------------+----------+
11 rows in set (0.00 sec)

MariaDB [fechas]> select * from repaso2 where nombre like '%z';
+--------+-------------------+--------+-----------------+----------+
| codigo | nombre            | sexo   | fechanacimiento | nrohijos |
+--------+-------------------+--------+-----------------+----------+
| 111222 | carlos ramirez    | hombre | 1969-04-04      |        2 |
| 333666 | marina ruiz       | mujer  | 1978-12-15      |        3 |
| 999111 | veronica gonzalez | mujer  | 1982-03-30      |        1 |
| 333777 | gladys bermudez   | mujer  | 1979-01-01      |        2 |
| 555777 | mario gomez       | hombre | 1982-05-29      |        2 |
| 111333 | andrea gutierrez  | mujer  | 1985-04-12      |        1 |
| 555333 | fernando perez    | hombre | 1980-11-11      |        4 |
+--------+-------------------+--------+-----------------+----------+
7 rows in set (0.00 sec)

MariaDB [fechas]> select count(*) from repaso2 where sexo= 'mujer' and nombre like '%z' ;
+----------+
| count(*) |
+----------+
|        4 |
+----------+
1 row in set (0.00 sec)

MariaDB [fechas]> select count(*) from repaso2 where year(fechanacimiento) between 1970 and 1979;
+----------+
| count(*) |
+----------+
|        4 |
+----------+
1 row in set (0.00 sec)

MariaDB [fechas]> select * from repaso2 where year (current_date()) - year(fechanacimiento) between '25' and '30' ;
Empty set (0.00 sec)

MariaDB [fechas]> select sum(nrohijos) from repaso2;
+---------------+
| sum(nrohijos) |
+---------------+
|            22 |
+---------------+
1 row in set (0.04 sec)

MariaDB [fechas]> select nrohijos, count(*) padres from repaso2 group by nrohijos;
+----------+--------+
| nrohijos | padres |
+----------+--------+
|        1 |      4 |
|        2 |      4 |
|        3 |      2 |
|        4 |      1 |
+----------+--------+
4 rows in set (0.04 sec)

MariaDB [fechas]> select count(*) from repaso2 where sexo= 'hombre' and nombre like 'carlos%' ;
+----------+
| count(*) |
+----------+
|        2 |
+----------+
1 row in set (0.00 sec)

MariaDB [fechas]> select * from repaso2 where nombre like '%carlos%';
+--------+------------------+--------+-----------------+----------+
| codigo | nombre           | sexo   | fechanacimiento | nrohijos |
+--------+------------------+--------+-----------------+----------+
| 111222 | carlos ramirez   | hombre | 1969-04-04      |        2 |
| 444777 | carlos sepulveda | hombre | 1974-01-10      |        1 |
+--------+------------------+--------+-----------------+----------+
2 rows in set (0.00 sec)

MariaDB [fechas]> select count(*) from repaso2 where year (current_date) - year (fechanacimiento)<=22 and sexo='mujer';
+----------+
| count(*) |
+----------+
|        0 |
+----------+
1 row in set (0.00 sec)

MariaDB [fechas]> select * from repaso2 where year (current_date) - year (fechanacimiento)<=22 and sexo='mujer';
Empty set (0.00 sec)

MariaDB [fechas]> select count(*) from repaso2 where year (current_date) - year (fechanacimiento)>30 and sexo='hombre';
+----------+
| count(*) |
+----------+
|        4 |
+----------+
1 row in set (0.00 sec)

MariaDB [fechas]> select count(*) from repaso2 where sexo='hombre' and nrohijos>1 and substr(fechanacimiento,1,4)< 1989;
+----------+
| count(*) |
+----------+
|        3 |
+----------+
1 row in set (0.03 sec)

MariaDB [fechas]> select count(*) from repaso2 where year (current_date) - year (fechanacimiento)>25 and sexo='mujer'and nrohijos between '1' and '3';
+----------+
| count(*) |
+----------+
|        7 |
+----------+
1 row in set (0.00 sec)

MariaDB [fechas]> select count(*) from repaso2 where sexo='mujer' and nrohijos>1 and substr(fechanacimiento,1,4)< 1994;
+----------+
| count(*) |
+----------+
|        4 |
+----------+
1 row in set (0.00 sec)

MariaDB [fechas]> select time (now());
+--------------+
| time (now()) |
+--------------+
| 18:38:36     |
+--------------+
1 row in set (0.04 sec)

MariaDB [fechas]> select current_date();
+----------------+
| current_date() |
+----------------+
| 2019-08-24     |
+----------------+
1 row in set (0.00 sec)

MariaDB [fechas]> exit