what type of diagram shows the relationships between tables
Entity–relationship model An ER model is typically implemented as a database. In a simple relational database implementation, each row of a table represents one instance of an entity type, and each field in a table represents an attribute type. In a relational database a relationship between entities is implemented by storing the primary key of one entity as a pointer or "foreign key" in the table of another entity
Population pyramid Population pyramids often contain continuous stacked-histogram bars, making it a horizontal bar diagram. The population size is depicted on the x-axis (horizontal) while the age-groups are represented on the y-axis (vertical).[3] The size of the population can either be measured as a percentage of the total population or by raw number. Males are conventionally shown on the left and females on the right. Population pyramids are often viewed as the most effective way to graphically depict the age and distribution of a population, partly because of the very clear image these pyramids represent.[4]A great deal of information about the population broken down by age and sex can be read from a population pyramid, and this can shed light on the extent of development and other aspects of the population.